{"schemaVersion":"1.0","revision":"fa961ab24277a91737c3","article":{"id":"scwiki-e3","topicId":"scwiki-topic-e3","code":"E3","slug":"electrostatic-gating","title":"Electrostatic gating: charge control and chemical changes","summary":"Read gate-tuned superconductivity through device history, capacitance, chemical controls and the actual transition criterion.","aliases":["electrostatic gating","gate tuning","ionic liquid","electric double layer","EDLT","quantum capacitance","field effect","electrochemical gating"],"evidenceTypes":["theory","experiment"],"relatedCodes":["E2","A1","A6","D11","B11"],"editorialStatus":"scoped-check","contentState":"pilot","modifiedAt":"2026-10-19T18:33:48.941677+00:00","review":{"checkedAt":"2026-10-20","scope":"Selected Caviglia, Lu and Sajadi author passages; Fatemi and Jeong final-journal passages and figures; limited Ueno and Ye source checks; bounded capacitance algebra. Follow-up: Sajadi S1 device geometry and S8 characteristic-criterion passages; source attribution/dates rechecked; local series-capacitance model comparison.","limitations":["Complete scientific acceptance, full supplements, remaining final-version comparisons and raw-data reproduction remain open.","Ueno identity and author summary do not supply a checked transition criterion; ZrNCl15.2K retains an unspecified criterion from an abstract.","Simple capacitance calculations do not establish mobile-carrier density or the absence of electrochemistry.","Device thresholds, BKT fits and normal-state reference temperatures cannot be treated as equivalent Tc values.","Selected supplementary sections do not constitute a complete supplement or independent scientific review. None of these records is certified thermodynamically equilibrated."]},"provenance":{"repository":"JackZH26/jzis-superconductivity","commit":"0a7c9d6696804ec26aa12f8eed68b55c9b3c0fcf","path":"E_tuning_parameters/E3_electrostatic_gating.md","sha256":"d2e5458129cccb307c7914380872fd66475978d4d43cb2f8e3851c26b4ca6608","sourceId":"file-514aa65d9361ea11"},"sourceMap":[{"startLine":1,"endLine":67,"targetSections":["scope","mathematical-assumptions","experimental-criteria","limits-and-disputes","discovery-implications","related-topics"],"decision":"edited-with-scoped-evidence","note":"Pinned source preserved; corrected Ueno/Ye attribution, distinguished gate chemistry and capacitance assumptions, retained device-specific criteria and limited review scopes."}],"references":[{"id":"source-e9e3a49b753191bc","doi":"10.1038/nature07576","title":"Electric field control of the LaAlO3/SrTiO3 interface ground state","year":2008,"url":"https://doi.org/10.1038/nature07576","publicationStatus":"journal-article","verification":{"scope":"selected-author-capacitance-history-and-BKT","checkedAt":"2026-10-18","evidenceUrl":"https://arxiv.org/pdf/0807.0585v1","note":"Author v1 submitted 3 July 2008; journal issue 4 December 2008. Selected pp. 3–8 and notes pp. 10–11 read; Fig. 3 p. 6 visually checked. Nonlinear capacitance integration, conditioning, BKT fit and normal-state temperatures retained. Final-version comparison and raw-data fits remain open."}},{"id":"source-3c6933981eaa417d","doi":"10.1038/nmat2298","title":"Electric-field-induced superconductivity in an insulator","year":2008,"url":"https://doi.org/10.1038/nmat2298","publicationStatus":"journal-article","verification":{"scope":"publisher-identity-and-author-institute-summary","checkedAt":"2026-10-20","evidenceUrl":"https://www.imr.tohoku.ac.jp/en/news/results/detail---id-817.html","note":"Published online 12 October 2008. Publisher metadata and authors institute summary identify SrTiO3, not ZrNCl. Original full methods and transition criterion were not read; no exact Tc is assigned here. Publisher dates and author-institution records rechecked; full text remains unavailable at checked official endpoints. No expanded transition-criterion claim."}},{"id":"source-831c3a9c5619ac1d","doi":"10.1038/nmat2587","title":"Liquid-gated interface superconductivity on an atomically flat film","year":2010,"url":"https://doi.org/10.1038/nmat2587","publicationStatus":"journal-article","verification":{"scope":"author-institution-abstract-and-publisher-dates","checkedAt":"2026-10-20","evidenceUrl":"https://research.rug.nl/en/publications/liquid-gated-interface-superconductivity-on-an-atomically-flat-fi/","note":"Ye et al.; online 22 November 2009, issue February 2010. Authors institutional abstract identifies ZrNCl and 15.2 K; publisher confirms dates. Full methods and exact onset/midpoint/zero criterion not reviewed. Publisher dates and author-institution records rechecked; full text remains unavailable at checked official endpoints. No expanded transition-criterion claim."}},{"id":"source-e8b9a66d143832fb","doi":"10.1126/science.1228006","title":"Superconducting Dome in a Gate-Tuned Band Insulator","year":2012,"url":"https://doi.org/10.1126/science.1228006","publicationStatus":"journal-article","verification":{"scope":"author-institution-abstract-only","checkedAt":"2026-10-18","evidenceUrl":"https://research.rug.nl/en/publications/superconducting-dome-in-a-gate-tuned-band-insulator/","note":"Published 30 November 2012. Authors institutional abstract supports a MoS2 dome using liquid and solid gating. Final PDF is embargoed there; full methods and raw data were not read."}},{"id":"source-cba51ab2111ccf0a","doi":"10.1126/science.aab2277","title":"Evidence for two-dimensional Ising superconductivity in gated MoS2","year":2015,"url":"https://doi.org/10.1126/science.aab2277","publicationStatus":"journal-article","verification":{"scope":"selected-author-v2-criteria-and-figure","checkedAt":"2026-10-18","evidenceUrl":"https://arxiv.org/pdf/1506.07620v2","note":"Author v2 submitted 5 August 2015; Science 350, 1353–1357. Selected v1 p. 3 and captions pp. 11–12, v2 captions pp. 11–13 and Fig. 1 p. 17 checked visually. Distinct 90%/50% criteria and model context retained; no complete spin-orbit derivation, supplement, final-version comparison or raw-data fit."}},{"id":"source-117f1ab64b772ff1","doi":"10.1126/science.aar4642","title":"Electrically tunable low-density superconductivity in a monolayer topological insulator","year":2018,"url":"https://doi.org/10.1126/science.aar4642","publicationStatus":"journal-article","verification":{"scope":"selected-final-journal-device-and-transition-criteria","checkedAt":"2026-10-18","evidenceUrl":"https://ciqm.harvard.edu/uploads/2/3/3/4/23349210/fatemi2018.pdf","note":"Online 25 October 2018; issue 23 November. Selected final journal pp. 1–3 read; p. 2 Figs. 1–2 visually checked. Device-specific thresholds and capacitance/Hall limits retained. Supplement, raw data and topological-gap verification not reviewed."}},{"id":"source-e8160470a5b03301","doi":"10.1126/science.aar4426","title":"Gate-induced superconductivity in a monolayer topological insulator","year":2018,"url":"https://doi.org/10.1126/science.aar4426","publicationStatus":"journal-article","verification":{"scope":"selected-author-density-definition-device-geometry-and-criteria","checkedAt":"2026-10-20","evidenceUrl":"https://arxiv.org/pdf/1809.04691v1","note":"Author v1 submitted 12 September 2018; journal online 25 October, issue 23 November. Selected pp. 2–4, S1/Table 1 pp. 9–10 and S8 p. 17 read; pp. 2, 3, 10 and 17 visually inspected. Geometric estimates, two device stacks, half-R(1 K), the finite 0.3 ohm floor at 20 mK and assumed current geometry remain distinct. Local series-capacitance arithmetic is not a carrier measurement. Complete supplement, raw-data reconstruction and final-version equivalence remain unchecked."}},{"id":"source-cd5c2b85b8e3a53c","doi":"10.1126/science.1230512","title":"Suppression of Metal-Insulator Transition in VO2 by Electric Field–Induced Oxygen Vacancy Formation","year":2013,"url":"https://doi.org/10.1126/science.1230512","publicationStatus":"journal-article","verification":{"scope":"selected-final-journal-chemical-controls","checkedAt":"2026-10-18","evidenceUrl":"https://bdt.semi.ac.cn/download/0.4525887994927481.pdf","note":"Published 22 March 2013. Selected PDF pp. 2–4 (journal pp. 1402–1404) and p. 3 Figs. 2–3 visually checked: reversible transport, liquid removal, XPS, isotope/SIMS controls and oxygen dependence. Full supplement and vacancy quantification not reviewed. This is not a superconducting Tc report."}}],"claims":[{"id":"scwiki-e3-claim-scope-1","sectionId":"scope","statement":"Gating specifies an applied-voltage protocol, not its microscopic mechanism. A solid dielectric can accumulate interfacial charge; an electrolyte can also change oxygen content, drive redox or move ions. Whether a particular experiment is predominantly electrostatic requires evidence about the actual material, temperature, time and voltage history. Reversible resistance alone is insufficient: Jeong's VO2 study demonstrated reversible conductance switching associated with oxygen-vacancy formation. That experiment is a mechanism control, not a superconducting discovery.","evidenceType":"experiment","sourceIds":["source-cd5c2b85b8e3a53c"],"conditions":"Gate history, device, capacitance convention, temperature reference, transport threshold and chemical controls remain distinct. A gated topological insulator is not automatically a topological superconductor.","verificationScope":"Selected original passages and figures, explicit limited abstracts and bounded circuit algebra; complete scientific acceptance remains open."},{"id":"scwiki-e3-claim-scope-2","sectionId":"scope","statement":"Keep the early platforms separate. Ueno and colleagues reported gated SrTiO3 in a paper published online on 12 October 2008. Ye and colleagues reported ZrNCl with a transition temperature of 15.2 K; that paper appeared online on 22 November 2009 and in the February 2010 issue. The online and issue dates describe one ZrNCl paper, not separate discoveries. The accessible author-institution records support the material and attribution; the checked ZrNCl abstract does not specify an onset, midpoint or zero-resistance criterion. No exact SrTiO3 transition temperature or common criterion is assigned from these limited records.","evidenceType":"editorial-analysis","sourceIds":["source-3c6933981eaa417d","source-831c3a9c5619ac1d"],"conditions":"Keep device M1/M2, gate geometry, assumed permittivity, estimated doping, temperature reference, resistance criterion and detection limit separate. No mobile-carrier measurement inferred from electrostatic arithmetic.","verificationScope":"Selected author v1 pp.2–4, S1/Table1 pp.9–10 and S8 p.17; pp.2/3/10/17 visually inspected where applicable. Ueno/Ye remain publisher/author-institution bibliographic and summary scope. No complete supplement, final comparison or raw-data fit.","sourceRelationship":"context-for-editorial-analysis","derivationNote":"Comparison of publisher bibliographic dates and author-institution material/abstract records. Full Ueno/Ye transition methods remain unreviewed."},{"id":"scwiki-e3-claim-mathematical-assumptions-1","sectionId":"mathematical-assumptions","statement":"For a uniform planar device with constant areal capacitance $C_A$, an electron-accumulation convention gives $\\Delta n_{2D}=C_A\\Delta V/e$, where $e>0$. If the measured total differential capacitance $C(V)=dQ/dV$ varies with voltage, use $\\Delta n_{2D}=(Ae)^{-1}\\int C(V)\\,dV$ for gated area $A$. Multiplying the endpoint capacitance by the entire voltage interval is generally wrong. Caviglia explicitly integrated the nonlinear response of the SrTiO3 dielectric.","evidenceType":"theory","sourceIds":["source-e9e3a49b753191bc"],"conditions":"Gate history, device, capacitance convention, temperature reference, transport threshold and chemical controls remain distinct. A gated topological insulator is not automatically a topological superconductor.","verificationScope":"Selected original passages and figures, explicit limited abstracts and bounded circuit algebra; complete scientific acceptance remains open.","sourceRelationship":"mixed-source-and-local-derivation","derivationNote":"Source experiments motivate the geometry and capacitance conditions. Displayed ideal circuit identities and unit conversions are local illustrative derivations, not source-measured carrier counts."},{"id":"scwiki-e3-claim-mathematical-assumptions-2","sectionId":"mathematical-assumptions","statement":"In a simple positive-capacitance model, $C_A^{-1}=C_{g,A}^{-1}+C_{q,A}^{-1}$ accounts for geometric and quantum capacitances in series, with $C_{q,A}=e^2\\partial n_{2D}/\\partial\\mu$. Traps, leakage, negative compressibility and spatially nonuniform channels require a richer treatment. For two gates, the ideal charge estimate is $en_{2D}=C_{t,A}(V_t-V_{t0})+C_{b,A}(V_b-V_{b0})$. Offset voltages and dielectric calibration are assumptions to report, not quantities fixed by the formula.","evidenceType":"theory","sourceIds":["source-e9e3a49b753191bc","source-117f1ab64b772ff1","source-e8160470a5b03301"],"conditions":"Gate history, device, capacitance convention, temperature reference, transport threshold and chemical controls remain distinct. A gated topological insulator is not automatically a topological superconductor.","verificationScope":"Selected original passages and figures, explicit limited abstracts and bounded circuit algebra; complete scientific acceptance remains open.","sourceRelationship":"mixed-source-and-local-derivation","derivationNote":"Source experiments motivate the geometry and capacitance conditions. Displayed ideal circuit identities and unit conversions are local illustrative derivations, not source-measured carrier counts."},{"id":"scwiki-e3-claim-mathematical-assumptions-3","sectionId":"mathematical-assumptions","statement":"Sajadi calls the gate-derived quantity a doping density, not a measured mobile-carrier density: correlations and edge conduction complicate that identification. The author's supplementary Table 1 uses AFM thicknesses and assumed relative permittivities of 4 for hBN and 3.9 for SiO2 to calculate geometric areal capacitances:\n\n| Device and gate | Dielectric stack | Calculated capacitance (nF/cm²) |\n| --- | --- | --- |\n| M1 top | 5.8 nm hBN | 611 |\n| M1 bottom | 18 nm hBN + 285 nm SiO2 | 11.4 |\n| M2 top | 8 nm hBN | 443 |\n| M2 bottom | 29 nm hBN | 122 |\n\nIn a uniform planar model, the layers in M1's bottom dielectric are in series. Omitting its SiO2 layer would overestimate that capacitance by about 17 times. This is a local calculation from rounded source inputs, not an experimental recalibration. The geometric approximation does not include every quantum-capacitance, contact-screening or trapping effect.\n\nEven a fixed estimated density does not specify both gate voltages: with constant capacitances, $c_t\\Delta V_t+c_b\\Delta V_b=0$ leaves the voltage-weighted sum unchanged while their difference changes. This identity does not demonstrate an unchanged transverse field, current path or superconducting state. Similarly, $Q=\\int I_gdt$ is transferred charge, without assigning its partition among the channel, traps and chemical reactions. Geometry arithmetic does not measure mobile carriers.","evidenceType":"theory","sourceIds":["source-e8160470a5b03301","source-cd5c2b85b8e3a53c"],"conditions":"Keep device M1/M2, gate geometry, assumed permittivity, estimated doping, temperature reference, resistance criterion and detection limit separate. No mobile-carrier measurement inferred from electrostatic arithmetic.","verificationScope":"Selected author v1 pp.2–4, S1/Table1 pp.9–10 and S8 p.17; pp.2/3/10/17 visually inspected where applicable. Ueno/Ye remain publisher/author-institution bibliographic and summary scope. No complete supplement, final comparison or raw-data fit.","sourceRelationship":"mixed-source-and-local-derivation","derivationNote":"Sajadi author v1 pp.2–3 and S1/Table1 supply definitions and geometric inputs. Series reconstruction and equal weighted-charge identities are local model checks; gate-current partition is an editorial inference limit informed by Jeong chemical controls."},{"id":"scwiki-e3-claim-experimental-criteria-1","sectionId":"experimental-criteria","statement":"Caviglia's LaAlO3/SrTiO3 device used the substrate as a back-gate dielectric. Its capacitance depended on sweep history; conditioning at the highest positive voltage produced reproducible sweeps, and the resulting zero-voltage state was not the as-grown state. The superconducting dome used temperatures extracted from a BKT resistance model, reaching approximately 0.310 K. The 0.400 K normal-state resistance and 1.5 K capacitance measurements are separate observables. Preserve the fit model and preparation history when comparing this dome with other systems.","evidenceType":"experiment","sourceIds":["source-e9e3a49b753191bc"],"conditions":"Gate history, device, capacitance convention, temperature reference, transport threshold and chemical controls remain distinct. A gated topological insulator is not automatically a topological superconductor.","verificationScope":"Selected original passages and figures, explicit limited abstracts and bounded circuit algebra; complete scientific acceptance remains open."},{"id":"scwiki-e3-claim-experimental-criteria-2","sectionId":"experimental-criteria","statement":"Fatemi's monolayer WTe2 device 1 illustrates why one transition has several temperatures. At bottom/top gate voltages 4/5 V, resistance reached 90% of its normal value near 0.820 K, 50% near 0.580 K and zero near 0.350 K. Device 2 reached a midpoint near 0.950 K but retained residual resistance attributed to a device imperfection. The two devices and criteria must not be collapsed into “zero resistance at 1 K.” Their Hall and capacitance estimates broadly agreed, with low-density deviations discussed as possibly inhomogeneous transport.","evidenceType":"experiment","sourceIds":["source-117f1ab64b772ff1"],"conditions":"Gate history, device, capacitance convention, temperature reference, transport threshold and chemical controls remain distinct. A gated topological insulator is not automatically a topological superconductor.","verificationScope":"Selected original passages and figures, explicit limited abstracts and bounded circuit algebra; complete scientific acceptance remains open."},{"id":"scwiki-e3-claim-experimental-criteria-3","sectionId":"experimental-criteria","statement":"MoS2 provides a related criterion warning. Ye established a gate-controlled dome in a band insulator. In Lu's later author manuscript, the phase-diagram panel uses 90% of the normal resistance at 15 K, whereas the remaining analysis uses 50%. A corresponding low-temperature state is labeled 2.63 K by the former criterion and 2.37 K by the latter. Keep those labels distinct from BKT temperatures or high-field boundaries. The layer-localization and spin–orbit interpretation also depends on the device model and field orientation.","evidenceType":"experiment","sourceIds":["source-e8b9a66d143832fb","source-cba51ab2111ccf0a"],"conditions":"Gate history, device, capacitance convention, temperature reference, transport threshold and chemical controls remain distinct. A gated topological insulator is not automatically a topological superconductor.","verificationScope":"Selected original passages and figures, explicit limited abstracts and bounded circuit algebra; complete scientific acceptance remains open."},{"id":"scwiki-e3-claim-experimental-criteria-4","sectionId":"experimental-criteria","statement":"Sajadi's M1 device uses the characteristic temperature $T_{1/2}$ where the measured resistance reaches half its value at 1 K. The 1 K reference is not $T_c$. Supplementary section S8 explicitly distinguishes characteristic parameters from precise critical parameters; gradual transitions and limited contact arrangements constrain their interpretation. Different fractions of the normal resistance produce different characteristic fields and derived lengths.\n\nAt 20 mK, M1 reaches a roughly 0.3 ohm experimental noise floor for the reported gate-derived density above $7\\times10^{12}\\,\\mathrm{cm}^{-2}$. This is finite measurement sensitivity under specified conditions, not exact mathematical zero or a transition at 20 mK. Its sheet-resistivity estimate additionally assumes that current spreads little outside a chosen rectangle, with width/length about 10. A four-terminal resistance does not remove uncertainty in that current path. No new numerical $T_c$ or thermodynamic phase boundary is extracted here.","evidenceType":"experiment","sourceIds":["source-e8160470a5b03301"],"conditions":"Keep device M1/M2, gate geometry, assumed permittivity, estimated doping, temperature reference, resistance criterion and detection limit separate. No mobile-carrier measurement inferred from electrostatic arithmetic.","verificationScope":"Selected author v1 pp.2–4, S1/Table1 pp.9–10 and S8 p.17; pp.2/3/10/17 visually inspected where applicable. Ueno/Ye remain publisher/author-institution bibliographic and summary scope. No complete supplement, final comparison or raw-data fit.","sourceRelationship":"direct-support","derivationNote":"Sajadi author v1 p.3 and selected S1/S8 passages distinguish a characteristic resistance threshold, finite measurement floor and assumed current geometry."},{"id":"scwiki-e3-claim-limits-and-disputes-1","sectionId":"limits-and-disputes","statement":"Jeong's VO2 evidence went beyond reversible transport: conductance persisted after the ionic liquid was removed, vanadium core-level spectra changed, and reverse gating in oxygen-18 produced an isotope depth profile measured by secondary-ion mass spectrometry. Ungated regions receiving the same isotope exposure served as controls. These results support chemical modification in those devices; they do not prove that every ionic-liquid-gated superconductor follows the same mechanism. Full supplementary procedures and quantitative vacancy reconstruction remain outside this scoped review.","evidenceType":"experiment","sourceIds":["source-cd5c2b85b8e3a53c"],"conditions":"Gate history, device, capacitance convention, temperature reference, transport threshold and chemical controls remain distinct. A gated topological insulator is not automatically a topological superconductor.","verificationScope":"Selected original passages and figures, explicit limited abstracts and bounded circuit algebra; complete scientific acceptance remains open."},{"id":"scwiki-e3-claim-limits-and-disputes-2","sectionId":"limits-and-disputes","statement":"A useful electrostatic interpretation therefore compares leakage and dwell-time behavior, sweep recovery, independent charge estimates, thickness dependence and before/after structural or chemical evidence. No single low-leakage threshold or unchanged spectrum proves the absence of all reactions. State the sensitivity and spatial sampling of each control. Conversely, hysteresis can arise from trapping in a dielectric and is not by itself proof of electrochemistry.","evidenceType":"experiment","sourceIds":["source-e9e3a49b753191bc","source-cd5c2b85b8e3a53c"],"conditions":"Gate history, device, capacitance convention, temperature reference, transport threshold and chemical controls remain distinct. A gated topological insulator is not automatically a topological superconductor.","verificationScope":"Selected original passages and figures, explicit limited abstracts and bounded circuit algebra; complete scientific acceptance remains open."},{"id":"scwiki-e3-claim-limits-and-disputes-3","sectionId":"limits-and-disputes","statement":"A gate-induced dome does not uniquely identify a pairing mechanism or a quantum critical point. Strong in-plane critical fields require analysis of orbital geometry, spin–orbit coupling and the chosen resistive threshold; they do not automatically establish triplet pairing. Switching a quantum spin Hall material into a superconducting regime creates an opportunity to investigate topology, but does not by itself demonstrate a topological superconducting gap or Majorana modes.","evidenceType":"experiment","sourceIds":["source-e8b9a66d143832fb","source-cba51ab2111ccf0a","source-117f1ab64b772ff1","source-e8160470a5b03301"],"conditions":"Gate history, device, capacitance convention, temperature reference, transport threshold and chemical controls remain distinct. A gated topological insulator is not automatically a topological superconductor.","verificationScope":"Selected original passages and figures, explicit limited abstracts and bounded circuit algebra; complete scientific acceptance remains open."},{"id":"scwiki-e3-claim-discovery-implications-1","sectionId":"discovery-implications","statement":"Treat the device and voltage history as part of the material record: dielectric or electrolyte, thickness, gate geometry, charging temperature, dwell time, leakage, reset protocol and independent carrier estimate. Separate superconducting onset, midpoint, measured zero and model-extracted BKT temperatures. Use chemistry-sensitive controls to decide whether a changed state belongs under electrostatic tuning or compositional modification. The source-linked records below preserve reported observations and explicit unknowns; they are not a ranking of intrinsic material performance. These records use unknown for equilibrium because their checked provenance does not establish a thermodynamic equilibrium state; this is not evidence of nonequilibrium.","evidenceType":"editorial-analysis","sourceIds":["source-e9e3a49b753191bc","source-cba51ab2111ccf0a","source-117f1ab64b772ff1","source-cd5c2b85b8e3a53c"],"conditions":"Gate history, device, capacitance convention, temperature reference, transport threshold and chemical controls remain distinct. A gated topological insulator is not automatically a topological superconductor.","verificationScope":"Selected original passages and figures, explicit limited abstracts and bounded circuit algebra; complete scientific acceptance remains open.","sourceRelationship":"context-for-editorial-analysis","derivationNote":"Editorial comparison of device/probe requirements; no synthesis ranking or equilibrium certification."}],"corrections":[{"id":"scwiki-e3-correction-1","description":"The inherited draft attributed ZrNCl near15K to Ueno2008 (nmat2298), which concerns SrTiO3. The ZrNCl15.2K source is Ye et al (nmat2587), online2009 and issue2010; both references remain with distinct material identities.","sourceId":"source-831c3a9c5619ac1d","scope":"Original bibliographic identity and authors institutional abstracts/summaries; ZrNCl full criterion not checked.","originalSourceLines":[],"targetSectionId":"scope"},{"id":"scwiki-e3-correction-gate-geometry-and-reference","description":"Expanded selected Sajadi geometry/criterion scope, kept 1K normalization and20mK measurement separate from Tc, and withheld equilibrium assertions lacking support. Ueno/Ye attribution and date comparison use explicit limited sources.","sourceId":"source-e8160470a5b03301","scope":"Selected source passages plus bounded local electrostatic arithmetic; no new experiment or full independent acceptance."}],"equationChecks":[{"targetSectionId":"mathematical-assumptions","tex":"\\Delta n_{2D}=\\frac{1}{Ae}\\int C(V)dV","check":"Analytic nonlinear-capacitance integral versus10000midpoint steps; endpoint product differs."},{"targetSectionId":"mathematical-assumptions","tex":"C_A^{-1}=C_{g,A}^{-1}+C_{q,A}^{-1}","check":"Four positive series-capacitance examples and unit conversions; no negative-compressibility model."},{"targetSectionId":"mathematical-assumptions","tex":"en_{2D}=C_{t,A}V_t+C_{b,A}V_b","check":"Rounded Fatemi15/8nm BN geometry with epsilonR3.5 and zero offsets yields density near5e12cm^-2; illustration, not a measured density."},{"targetSectionId":"mathematical-assumptions","tex":"C_A^{-1}=\\sum_i d_i/(\\epsilon_0\\epsilon_{r,i})","check":"Sajadi M1/M2 four published rounded capacitances reproduced from stated geometry within0.2%; independent series check and8constant-estimated-charge voltage identities. Local model only."}],"materialCases":[{"id":"scwiki-e3-material-1","formula":"LaAlO3/SrTiO3","sample":"Caviglia gate-tuned dome maximum","recordType":"experiment","reportedTemperatureK":0.31,"tcK":0.31,"temperatureKind":"transition","temperatureNote":"Approximate maximum from a BKT fit; not an onset or measured-zero temperature. Thermodynamic equilibrium is unverified in the checked provenance.","criterion":"BKT-resistance-fit","pressureRegime":"ambient","pressureGPa":null,"equilibrium":"unknown","probe":"Four-point sheet resistance","sourceId":"source-e9e3a49b753191bc"},{"id":"scwiki-e3-material-2","formula":"WTe2","sample":"Fatemi device1 Vbg4V/Vtg5V","recordType":"experiment","reportedTemperatureK":0.82,"tcK":0.82,"temperatureKind":"transition","temperatureNote":"Approximate onset at90percent normal resistance; same device transition has lower midpoint and zero. Thermodynamic equilibrium is unverified in the checked provenance.","criterion":"resistance-90-percent-normal","pressureRegime":"ambient","pressureGPa":null,"equilibrium":"unknown","probe":"Four-probe resistance","sourceId":"source-117f1ab64b772ff1","aliases":["tungsten ditelluride"]},{"id":"scwiki-e3-material-3","formula":"WTe2","sample":"Fatemi device1 Vbg4V/Vtg5V","recordType":"experiment","reportedTemperatureK":0.58,"tcK":0.58,"temperatureKind":"transition","temperatureNote":"Approximate midpoint, distinct from onset and zero. Thermodynamic equilibrium is unverified in the checked provenance.","criterion":"resistance-50-percent-normal","pressureRegime":"ambient","pressureGPa":null,"equilibrium":"unknown","probe":"Four-probe resistance","sourceId":"source-117f1ab64b772ff1","aliases":["tungsten ditelluride"]},{"id":"scwiki-e3-material-4","formula":"WTe2","sample":"Fatemi device1 Vbg4V/Vtg5V","recordType":"experiment","reportedTemperatureK":0.35,"tcK":0.35,"temperatureKind":"transition","temperatureNote":"Approximate measured zero; not mathematical proof of zero uncertainty. Thermodynamic equilibrium is unverified in the checked provenance.","criterion":"zero-resistance","pressureRegime":"ambient","pressureGPa":null,"equilibrium":"unknown","probe":"Four-probe resistance","sourceId":"source-117f1ab64b772ff1","aliases":["tungsten ditelluride"]},{"id":"scwiki-e3-material-5","formula":"WTe2","sample":"Fatemi device2 maximum midpoint","recordType":"experiment","reportedTemperatureK":0.95,"tcK":0.95,"temperatureKind":"transition","temperatureNote":"Residual resistance persists due to reported device imperfection; not zero-resistance at0.95K. Thermodynamic equilibrium is unverified in the checked provenance.","criterion":"resistance-50-percent-normal","pressureRegime":"ambient","pressureGPa":null,"equilibrium":"unknown","probe":"Four-probe resistance","sourceId":"source-117f1ab64b772ff1","aliases":["tungsten ditelluride"]},{"id":"scwiki-e3-material-6","formula":"MoS2","sample":"Lu D1 low-temperature state; authorv2 Fig1D","recordType":"experiment","reportedTemperatureK":2.63,"tcK":2.63,"temperatureKind":"transition","temperatureNote":"Phase-diagram criterion relative to normal resistance at15K; same state midpoint2.37K. Thermodynamic equilibrium is unverified in the checked provenance.","criterion":"resistance-90-percent-normal","pressureRegime":"ambient","pressureGPa":null,"equilibrium":"unknown","probe":"Gate-induced sheet resistance","sourceId":"source-cba51ab2111ccf0a","aliases":["molybdenum disulfide"]},{"id":"scwiki-e3-material-7","formula":"MoS2","sample":"Lu D1 low-temperature state; authorv2 Fig1E","recordType":"experiment","reportedTemperatureK":2.37,"tcK":2.37,"temperatureKind":"transition","temperatureNote":"Midpoint criterion used for subsequent field analysis; not the90percent phase-diagram label. Thermodynamic equilibrium is unverified in the checked provenance.","criterion":"resistance-50-percent-normal","pressureRegime":"ambient","pressureGPa":null,"equilibrium":"unknown","probe":"Gate-induced sheet resistance","sourceId":"source-cba51ab2111ccf0a","aliases":["molybdenum disulfide"]},{"id":"scwiki-e3-material-8","formula":"ZrNCl","sample":"Ye liquid-gated atomically flat film","recordType":"experiment","reportedTemperatureK":15.2,"tcK":15.2,"temperatureKind":"transition","temperatureNote":"Exact onset/midpoint/zero criterion not independently reviewed. Not Ueno2008SrTiO3. Thermodynamic equilibrium is unverified in the checked provenance.","criterion":"transition-unspecified","pressureRegime":"ambient","pressureGPa":null,"equilibrium":"unknown","probe":"Field-induced superconductivity; abstract-level evidence","sourceId":"source-831c3a9c5619ac1d"},{"id":"scwiki-e3-material-9","formula":"WTe2","sample":"Sajadi M1 author v1; gate-derived doping above 7e12 cm^-2","recordType":"experiment","reportedTemperatureK":0.02,"tcK":null,"temperatureKind":"measurement","temperatureNote":"At 20 mK, M1 reaches an approximately 0.3 ohm noise floor for gate-derived doping above 7 × 10^12 cm^-2. This is finite sensitivity, not exact zero or a 20 mK transition. Density is capacitance-derived, not an independent mobile-carrier measurement. Thermodynamic equilibrium remains unverified.","criterion":"resistance-noise-floor-observation","pressureRegime":"ambient","pressureGPa":null,"equilibrium":"unknown","probe":"Four-terminal differential resistance","sourceId":"source-e8160470a5b03301","aliases":["tungsten ditelluride","Sajadi M1"]},{"id":"scwiki-e3-material-10","formula":"MoS2","sample":"Lu normal resistance reference","recordType":"experiment","reportedTemperatureK":15,"tcK":null,"temperatureKind":"normal-state","temperatureNote":"Normalization reference used in the90percent criterion, not superconducting Tc. Thermodynamic equilibrium is unverified in the checked provenance.","criterion":"normal-resistance-reference","pressureRegime":"ambient","pressureGPa":null,"equilibrium":"unknown","probe":"Sheet resistance","sourceId":"source-cba51ab2111ccf0a","aliases":["molybdenum disulfide"]},{"id":"scwiki-e3-material-11","formula":"VO2","sample":"Jeong reversible-gating chemical control","recordType":"experiment","reportedTemperatureK":300,"tcK":null,"temperatureKind":"measurement","temperatureNote":"Gating temperature for the Fig2protocol; no superconducting transition reported. Thermodynamic equilibrium is unverified in the checked provenance.","criterion":"gate-application-temperature","pressureRegime":"ambient","pressureGPa":null,"equilibrium":"unknown","probe":"Transport, XPS and isotope/SIMS controls","sourceId":"source-cd5c2b85b8e3a53c"},{"id":"scwiki-e3-material-12","formula":"WTe2","sample":"Sajadi M1 reference for the characteristic half-resistance temperature","recordType":"experiment","reportedTemperatureK":1,"tcK":null,"temperatureKind":"normal-state","temperatureNote":"1 K is the resistance normalization reference for T1/2; it is not a transition temperature. No new numerical Tc is extracted. Thermodynamic equilibrium remains unverified.","criterion":"normal-resistance-reference","pressureRegime":"ambient","pressureGPa":null,"equilibrium":"unknown","probe":"Four-terminal resistance reference","sourceId":"source-e8160470a5b03301","aliases":["tungsten ditelluride","Sajadi M1"]}],"body":"## Scope\n\nGating specifies an applied-voltage protocol, not its microscopic mechanism. A solid dielectric can accumulate interfacial charge; an electrolyte can also change oxygen content, drive redox or move ions. Whether a particular experiment is predominantly electrostatic requires evidence about the actual material, temperature, time and voltage history. Reversible resistance alone is insufficient: Jeong's VO2 study demonstrated reversible conductance switching associated with oxygen-vacancy formation. That experiment is a mechanism control, not a superconducting discovery. [R8](#ref-source-cd5c2b85b8e3a53c)\n\nKeep the early platforms separate. Ueno and colleagues reported gated SrTiO3 in a paper published online on 12 October 2008. Ye and colleagues reported ZrNCl with a transition temperature of 15.2 K; that paper appeared online on 22 November 2009 and in the February 2010 issue. The online and issue dates describe one ZrNCl paper, not separate discoveries. The accessible author-institution records support the material and attribution; the checked ZrNCl abstract does not specify an onset, midpoint or zero-resistance criterion. No exact SrTiO3 transition temperature or common criterion is assigned from these limited records. [R2](#ref-source-3c6933981eaa417d) [R3](#ref-source-831c3a9c5619ac1d)\n\n## Mathematical assumptions\n\nFor a uniform planar device with constant areal capacitance $C_A$, an electron-accumulation convention gives $\\Delta n_{2D}=C_A\\Delta V/e$, where $e>0$. If the measured total differential capacitance $C(V)=dQ/dV$ varies with voltage, use $\\Delta n_{2D}=(Ae)^{-1}\\int C(V)\\,dV$ for gated area $A$. Multiplying the endpoint capacitance by the entire voltage interval is generally wrong. Caviglia explicitly integrated the nonlinear response of the SrTiO3 dielectric. [R1](#ref-source-e9e3a49b753191bc)\n\nIn a simple positive-capacitance model, $C_A^{-1}=C_{g,A}^{-1}+C_{q,A}^{-1}$ accounts for geometric and quantum capacitances in series, with $C_{q,A}=e^2\\partial n_{2D}/\\partial\\mu$. Traps, leakage, negative compressibility and spatially nonuniform channels require a richer treatment. For two gates, the ideal charge estimate is $en_{2D}=C_{t,A}(V_t-V_{t0})+C_{b,A}(V_b-V_{b0})$. Offset voltages and dielectric calibration are assumptions to report, not quantities fixed by the formula. [R1](#ref-source-e9e3a49b753191bc) [R6](#ref-source-117f1ab64b772ff1) [R7](#ref-source-e8160470a5b03301)\n\nSajadi calls the gate-derived quantity a doping density, not a measured mobile-carrier density: correlations and edge conduction complicate that identification. The author's supplementary Table 1 uses AFM thicknesses and assumed relative permittivities of 4 for hBN and 3.9 for SiO2 to calculate geometric areal capacitances:\n\n| Device and gate | Dielectric stack | Calculated capacitance (nF/cm²) |\n| --- | --- | --- |\n| M1 top | 5.8 nm hBN | 611 |\n| M1 bottom | 18 nm hBN + 285 nm SiO2 | 11.4 |\n| M2 top | 8 nm hBN | 443 |\n| M2 bottom | 29 nm hBN | 122 |\n\nIn a uniform planar model, the layers in M1's bottom dielectric are in series. Omitting its SiO2 layer would overestimate that capacitance by about 17 times. This is a local calculation from rounded source inputs, not an experimental recalibration. The geometric approximation does not include every quantum-capacitance, contact-screening or trapping effect.\n\nEven a fixed estimated density does not specify both gate voltages: with constant capacitances, $c_t\\Delta V_t+c_b\\Delta V_b=0$ leaves the voltage-weighted sum unchanged while their difference changes. This identity does not demonstrate an unchanged transverse field, current path or superconducting state. Similarly, $Q=\\int I_gdt$ is transferred charge, without assigning its partition among the channel, traps and chemical reactions. Geometry arithmetic does not measure mobile carriers. [R7](#ref-source-e8160470a5b03301) [R8](#ref-source-cd5c2b85b8e3a53c)\n\n## Experimental criteria\n\nCaviglia's LaAlO3/SrTiO3 device used the substrate as a back-gate dielectric. Its capacitance depended on sweep history; conditioning at the highest positive voltage produced reproducible sweeps, and the resulting zero-voltage state was not the as-grown state. The superconducting dome used temperatures extracted from a BKT resistance model, reaching approximately 0.310 K. The 0.400 K normal-state resistance and 1.5 K capacitance measurements are separate observables. Preserve the fit model and preparation history when comparing this dome with other systems. [R1](#ref-source-e9e3a49b753191bc)\n\nFatemi's monolayer WTe2 device 1 illustrates why one transition has several temperatures. At bottom/top gate voltages 4/5 V, resistance reached 90% of its normal value near 0.820 K, 50% near 0.580 K and zero near 0.350 K. Device 2 reached a midpoint near 0.950 K but retained residual resistance attributed to a device imperfection. The two devices and criteria must not be collapsed into “zero resistance at 1 K.” Their Hall and capacitance estimates broadly agreed, with low-density deviations discussed as possibly inhomogeneous transport. [R6](#ref-source-117f1ab64b772ff1)\n\nMoS2 provides a related criterion warning. Ye established a gate-controlled dome in a band insulator. In Lu's later author manuscript, the phase-diagram panel uses 90% of the normal resistance at 15 K, whereas the remaining analysis uses 50%. A corresponding low-temperature state is labeled 2.63 K by the former criterion and 2.37 K by the latter. Keep those labels distinct from BKT temperatures or high-field boundaries. The layer-localization and spin–orbit interpretation also depends on the device model and field orientation. [R4](#ref-source-e8b9a66d143832fb) [R5](#ref-source-cba51ab2111ccf0a)\n\nSajadi's M1 device uses the characteristic temperature $T_{1/2}$ where the measured resistance reaches half its value at 1 K. The 1 K reference is not $T_c$. Supplementary section S8 explicitly distinguishes characteristic parameters from precise critical parameters; gradual transitions and limited contact arrangements constrain their interpretation. Different fractions of the normal resistance produce different characteristic fields and derived lengths.\n\nAt 20 mK, M1 reaches a roughly 0.3 ohm experimental noise floor for the reported gate-derived density above $7\\times10^{12}\\,\\mathrm{cm}^{-2}$. This is finite measurement sensitivity under specified conditions, not exact mathematical zero or a transition at 20 mK. Its sheet-resistivity estimate additionally assumes that current spreads little outside a chosen rectangle, with width/length about 10. A four-terminal resistance does not remove uncertainty in that current path. No new numerical $T_c$ or thermodynamic phase boundary is extracted here. [R7](#ref-source-e8160470a5b03301)\n\n## Limits and disputes\n\nJeong's VO2 evidence went beyond reversible transport: conductance persisted after the ionic liquid was removed, vanadium core-level spectra changed, and reverse gating in oxygen-18 produced an isotope depth profile measured by secondary-ion mass spectrometry. Ungated regions receiving the same isotope exposure served as controls. These results support chemical modification in those devices; they do not prove that every ionic-liquid-gated superconductor follows the same mechanism. Full supplementary procedures and quantitative vacancy reconstruction remain outside this scoped review. [R8](#ref-source-cd5c2b85b8e3a53c)\n\nA useful electrostatic interpretation therefore compares leakage and dwell-time behavior, sweep recovery, independent charge estimates, thickness dependence and before/after structural or chemical evidence. No single low-leakage threshold or unchanged spectrum proves the absence of all reactions. State the sensitivity and spatial sampling of each control. Conversely, hysteresis can arise from trapping in a dielectric and is not by itself proof of electrochemistry. [R1](#ref-source-e9e3a49b753191bc) [R8](#ref-source-cd5c2b85b8e3a53c)\n\nA gate-induced dome does not uniquely identify a pairing mechanism or a quantum critical point. Strong in-plane critical fields require analysis of orbital geometry, spin–orbit coupling and the chosen resistive threshold; they do not automatically establish triplet pairing. Switching a quantum spin Hall material into a superconducting regime creates an opportunity to investigate topology, but does not by itself demonstrate a topological superconducting gap or Majorana modes. [R4](#ref-source-e8b9a66d143832fb) [R5](#ref-source-cba51ab2111ccf0a) [R6](#ref-source-117f1ab64b772ff1) [R7](#ref-source-e8160470a5b03301)\n\n## Discovery implications\n\nTreat the device and voltage history as part of the material record: dielectric or electrolyte, thickness, gate geometry, charging temperature, dwell time, leakage, reset protocol and independent carrier estimate. Separate superconducting onset, midpoint, measured zero and model-extracted BKT temperatures. Use chemistry-sensitive controls to decide whether a changed state belongs under electrostatic tuning or compositional modification. The source-linked records below preserve reported observations and explicit unknowns; they are not a ranking of intrinsic material performance. These records use unknown for equilibrium because their checked provenance does not establish a thermodynamic equilibrium state; this is not evidence of nonequilibrium. [R1](#ref-source-e9e3a49b753191bc) [R5](#ref-source-cba51ab2111ccf0a) [R6](#ref-source-117f1ab64b772ff1) [R8](#ref-source-cd5c2b85b8e3a53c)\n\n## Related topics\n\nContinue with [chemical doping](/scwiki/chemical-doping), [zero resistance](/scwiki/zero-resistance), [critical fields](/scwiki/critical-fields), [two-dimensional superconductivity](/scwiki/two-dimensional-interfaces) and [topological superconductivity](/scwiki/topological-superconductivity).","revision":"44a94ba4b79eef5b0a68","sections":[{"id":"scope","title":"Scope","markdown":"## Scope\n\nGating specifies an applied-voltage protocol, not its microscopic mechanism. A solid dielectric can accumulate interfacial charge; an electrolyte can also change oxygen content, drive redox or move ions. Whether a particular experiment is predominantly electrostatic requires evidence about the actual material, temperature, time and voltage history. Reversible resistance alone is insufficient: Jeong's VO2 study demonstrated reversible conductance switching associated with oxygen-vacancy formation. That experiment is a mechanism control, not a superconducting discovery. [R8](#ref-source-cd5c2b85b8e3a53c)\n\nKeep the early platforms separate. Ueno and colleagues reported gated SrTiO3 in a paper published online on 12 October 2008. Ye and colleagues reported ZrNCl with a transition temperature of 15.2 K; that paper appeared online on 22 November 2009 and in the February 2010 issue. The online and issue dates describe one ZrNCl paper, not separate discoveries. The accessible author-institution records support the material and attribution; the checked ZrNCl abstract does not specify an onset, midpoint or zero-resistance criterion. No exact SrTiO3 transition temperature or common criterion is assigned from these limited records. [R2](#ref-source-3c6933981eaa417d) [R3](#ref-source-831c3a9c5619ac1d)"},{"id":"mathematical-assumptions","title":"Mathematical assumptions","markdown":"## Mathematical assumptions\n\nFor a uniform planar device with constant areal capacitance $C_A$, an electron-accumulation convention gives $\\Delta n_{2D}=C_A\\Delta V/e$, where $e>0$. If the measured total differential capacitance $C(V)=dQ/dV$ varies with voltage, use $\\Delta n_{2D}=(Ae)^{-1}\\int C(V)\\,dV$ for gated area $A$. Multiplying the endpoint capacitance by the entire voltage interval is generally wrong. Caviglia explicitly integrated the nonlinear response of the SrTiO3 dielectric. [R1](#ref-source-e9e3a49b753191bc)\n\nIn a simple positive-capacitance model, $C_A^{-1}=C_{g,A}^{-1}+C_{q,A}^{-1}$ accounts for geometric and quantum capacitances in series, with $C_{q,A}=e^2\\partial n_{2D}/\\partial\\mu$. Traps, leakage, negative compressibility and spatially nonuniform channels require a richer treatment. For two gates, the ideal charge estimate is $en_{2D}=C_{t,A}(V_t-V_{t0})+C_{b,A}(V_b-V_{b0})$. Offset voltages and dielectric calibration are assumptions to report, not quantities fixed by the formula. [R1](#ref-source-e9e3a49b753191bc) [R6](#ref-source-117f1ab64b772ff1) [R7](#ref-source-e8160470a5b03301)\n\nSajadi calls the gate-derived quantity a doping density, not a measured mobile-carrier density: correlations and edge conduction complicate that identification. The author's supplementary Table 1 uses AFM thicknesses and assumed relative permittivities of 4 for hBN and 3.9 for SiO2 to calculate geometric areal capacitances:\n\n| Device and gate | Dielectric stack | Calculated capacitance (nF/cm²) |\n| --- | --- | --- |\n| M1 top | 5.8 nm hBN | 611 |\n| M1 bottom | 18 nm hBN + 285 nm SiO2 | 11.4 |\n| M2 top | 8 nm hBN | 443 |\n| M2 bottom | 29 nm hBN | 122 |\n\nIn a uniform planar model, the layers in M1's bottom dielectric are in series. Omitting its SiO2 layer would overestimate that capacitance by about 17 times. This is a local calculation from rounded source inputs, not an experimental recalibration. The geometric approximation does not include every quantum-capacitance, contact-screening or trapping effect.\n\nEven a fixed estimated density does not specify both gate voltages: with constant capacitances, $c_t\\Delta V_t+c_b\\Delta V_b=0$ leaves the voltage-weighted sum unchanged while their difference changes. This identity does not demonstrate an unchanged transverse field, current path or superconducting state. Similarly, $Q=\\int I_gdt$ is transferred charge, without assigning its partition among the channel, traps and chemical reactions. Geometry arithmetic does not measure mobile carriers. [R7](#ref-source-e8160470a5b03301) [R8](#ref-source-cd5c2b85b8e3a53c)"},{"id":"experimental-criteria","title":"Experimental criteria","markdown":"## Experimental criteria\n\nCaviglia's LaAlO3/SrTiO3 device used the substrate as a back-gate dielectric. Its capacitance depended on sweep history; conditioning at the highest positive voltage produced reproducible sweeps, and the resulting zero-voltage state was not the as-grown state. The superconducting dome used temperatures extracted from a BKT resistance model, reaching approximately 0.310 K. The 0.400 K normal-state resistance and 1.5 K capacitance measurements are separate observables. Preserve the fit model and preparation history when comparing this dome with other systems. [R1](#ref-source-e9e3a49b753191bc)\n\nFatemi's monolayer WTe2 device 1 illustrates why one transition has several temperatures. At bottom/top gate voltages 4/5 V, resistance reached 90% of its normal value near 0.820 K, 50% near 0.580 K and zero near 0.350 K. Device 2 reached a midpoint near 0.950 K but retained residual resistance attributed to a device imperfection. The two devices and criteria must not be collapsed into “zero resistance at 1 K.” Their Hall and capacitance estimates broadly agreed, with low-density deviations discussed as possibly inhomogeneous transport. [R6](#ref-source-117f1ab64b772ff1)\n\nMoS2 provides a related criterion warning. Ye established a gate-controlled dome in a band insulator. In Lu's later author manuscript, the phase-diagram panel uses 90% of the normal resistance at 15 K, whereas the remaining analysis uses 50%. A corresponding low-temperature state is labeled 2.63 K by the former criterion and 2.37 K by the latter. Keep those labels distinct from BKT temperatures or high-field boundaries. The layer-localization and spin–orbit interpretation also depends on the device model and field orientation. [R4](#ref-source-e8b9a66d143832fb) [R5](#ref-source-cba51ab2111ccf0a)\n\nSajadi's M1 device uses the characteristic temperature $T_{1/2}$ where the measured resistance reaches half its value at 1 K. The 1 K reference is not $T_c$. Supplementary section S8 explicitly distinguishes characteristic parameters from precise critical parameters; gradual transitions and limited contact arrangements constrain their interpretation. Different fractions of the normal resistance produce different characteristic fields and derived lengths.\n\nAt 20 mK, M1 reaches a roughly 0.3 ohm experimental noise floor for the reported gate-derived density above $7\\times10^{12}\\,\\mathrm{cm}^{-2}$. This is finite measurement sensitivity under specified conditions, not exact mathematical zero or a transition at 20 mK. Its sheet-resistivity estimate additionally assumes that current spreads little outside a chosen rectangle, with width/length about 10. A four-terminal resistance does not remove uncertainty in that current path. No new numerical $T_c$ or thermodynamic phase boundary is extracted here. [R7](#ref-source-e8160470a5b03301)"},{"id":"limits-and-disputes","title":"Limits and disputes","markdown":"## Limits and disputes\n\nJeong's VO2 evidence went beyond reversible transport: conductance persisted after the ionic liquid was removed, vanadium core-level spectra changed, and reverse gating in oxygen-18 produced an isotope depth profile measured by secondary-ion mass spectrometry. Ungated regions receiving the same isotope exposure served as controls. These results support chemical modification in those devices; they do not prove that every ionic-liquid-gated superconductor follows the same mechanism. Full supplementary procedures and quantitative vacancy reconstruction remain outside this scoped review. [R8](#ref-source-cd5c2b85b8e3a53c)\n\nA useful electrostatic interpretation therefore compares leakage and dwell-time behavior, sweep recovery, independent charge estimates, thickness dependence and before/after structural or chemical evidence. No single low-leakage threshold or unchanged spectrum proves the absence of all reactions. State the sensitivity and spatial sampling of each control. Conversely, hysteresis can arise from trapping in a dielectric and is not by itself proof of electrochemistry. [R1](#ref-source-e9e3a49b753191bc) [R8](#ref-source-cd5c2b85b8e3a53c)\n\nA gate-induced dome does not uniquely identify a pairing mechanism or a quantum critical point. Strong in-plane critical fields require analysis of orbital geometry, spin–orbit coupling and the chosen resistive threshold; they do not automatically establish triplet pairing. Switching a quantum spin Hall material into a superconducting regime creates an opportunity to investigate topology, but does not by itself demonstrate a topological superconducting gap or Majorana modes. [R4](#ref-source-e8b9a66d143832fb) [R5](#ref-source-cba51ab2111ccf0a) [R6](#ref-source-117f1ab64b772ff1) [R7](#ref-source-e8160470a5b03301)"},{"id":"discovery-implications","title":"Discovery implications","markdown":"## Discovery implications\n\nTreat the device and voltage history as part of the material record: dielectric or electrolyte, thickness, gate geometry, charging temperature, dwell time, leakage, reset protocol and independent carrier estimate. Separate superconducting onset, midpoint, measured zero and model-extracted BKT temperatures. Use chemistry-sensitive controls to decide whether a changed state belongs under electrostatic tuning or compositional modification. The source-linked records below preserve reported observations and explicit unknowns; they are not a ranking of intrinsic material performance. These records use unknown for equilibrium because their checked provenance does not establish a thermodynamic equilibrium state; this is not evidence of nonequilibrium. [R1](#ref-source-e9e3a49b753191bc) [R5](#ref-source-cba51ab2111ccf0a) [R6](#ref-source-117f1ab64b772ff1) [R8](#ref-source-cd5c2b85b8e3a53c)"},{"id":"related-topics","title":"Related topics","markdown":"## Related topics\n\nContinue with [chemical doping](/scwiki/chemical-doping), [zero resistance](/scwiki/zero-resistance), [critical fields](/scwiki/critical-fields), [two-dimensional superconductivity](/scwiki/two-dimensional-interfaces) and [topological superconductivity](/scwiki/topological-superconductivity)."},{"id":"material-cases","title":"Material cases","markdown":"## Material cases\n\nValues describe individual reports, not a ranking. Unknown means the checked source did not supply the field at this review scope.\n\n| Material and sample | Reported temperature | Criterion | Probe | Pressure | State | Evidence |\n|---|---|---|---|---|---|---|\n| LaAlO3/SrTiO3; Caviglia gate-tuned dome maximum | 0.31 K; Approximate maximum from a BKT fit; not an onset or measured-zero temperature. Thermodynamic equilibrium is unverified in the checked provenance. | transition; BKT-resistance-fit | Four-point sheet resistance | ambient; unknown GPa | unknown | experiment; [source](#ref-source-e9e3a49b753191bc) |\n| WTe2 (aliases: tungsten ditelluride); Fatemi device1 Vbg4V/Vtg5V | 0.82 K; Approximate onset at90percent normal resistance; same device transition has lower midpoint and zero. Thermodynamic equilibrium is unverified in the checked provenance. | transition; resistance-90-percent-normal | Four-probe resistance | ambient; unknown GPa | unknown | experiment; [source](#ref-source-117f1ab64b772ff1) |\n| WTe2 (aliases: tungsten ditelluride); Fatemi device1 Vbg4V/Vtg5V | 0.58 K; Approximate midpoint, distinct from onset and zero. Thermodynamic equilibrium is unverified in the checked provenance. | transition; resistance-50-percent-normal | Four-probe resistance | ambient; unknown GPa | unknown | experiment; [source](#ref-source-117f1ab64b772ff1) |\n| WTe2 (aliases: tungsten ditelluride); Fatemi device1 Vbg4V/Vtg5V | 0.35 K; Approximate measured zero; not mathematical proof of zero uncertainty. Thermodynamic equilibrium is unverified in the checked provenance. | transition; zero-resistance | Four-probe resistance | ambient; unknown GPa | unknown | experiment; [source](#ref-source-117f1ab64b772ff1) |\n| WTe2 (aliases: tungsten ditelluride); Fatemi device2 maximum midpoint | 0.95 K; Residual resistance persists due to reported device imperfection; not zero-resistance at0.95K. Thermodynamic equilibrium is unverified in the checked provenance. | transition; resistance-50-percent-normal | Four-probe resistance | ambient; unknown GPa | unknown | experiment; [source](#ref-source-117f1ab64b772ff1) |\n| MoS2 (aliases: molybdenum disulfide); Lu D1 low-temperature state; authorv2 Fig1D | 2.63 K; Phase-diagram criterion relative to normal resistance at15K; same state midpoint2.37K. Thermodynamic equilibrium is unverified in the checked provenance. | transition; resistance-90-percent-normal | Gate-induced sheet resistance | ambient; unknown GPa | unknown | experiment; [source](#ref-source-cba51ab2111ccf0a) |\n| MoS2 (aliases: molybdenum disulfide); Lu D1 low-temperature state; authorv2 Fig1E | 2.37 K; Midpoint criterion used for subsequent field analysis; not the90percent phase-diagram label. Thermodynamic equilibrium is unverified in the checked provenance. | transition; resistance-50-percent-normal | Gate-induced sheet resistance | ambient; unknown GPa | unknown | experiment; [source](#ref-source-cba51ab2111ccf0a) |\n| ZrNCl; Ye liquid-gated atomically flat film | 15.2 K; Exact onset/midpoint/zero criterion not independently reviewed. Not Ueno2008SrTiO3. Thermodynamic equilibrium is unverified in the checked provenance. | transition; transition-unspecified | Field-induced superconductivity; abstract-level evidence | ambient; unknown GPa | unknown | experiment; [source](#ref-source-831c3a9c5619ac1d) |\n| WTe2 (aliases: tungsten ditelluride, Sajadi M1); Sajadi M1 author v1; gate-derived doping above 7e12 cm^-2 | 0.02 K; At 20 mK, M1 reaches an approximately 0.3 ohm noise floor for gate-derived doping above 7 × 10^12 cm^-2. This is finite sensitivity, not exact zero or a 20 mK transition. Density is capacitance-derived, not an independent mobile-carrier measurement. Thermodynamic equilibrium remains unverified. | measurement; resistance-noise-floor-observation | Four-terminal differential resistance | ambient; unknown GPa | unknown | experiment; [source](#ref-source-e8160470a5b03301) |\n| MoS2 (aliases: molybdenum disulfide); Lu normal resistance reference | 15 K; Normalization reference used in the90percent criterion, not superconducting Tc. Thermodynamic equilibrium is unverified in the checked provenance. | normal-state; normal-resistance-reference | Sheet resistance | ambient; unknown GPa | unknown | experiment; [source](#ref-source-cba51ab2111ccf0a) |\n| VO2; Jeong reversible-gating chemical control | 300 K; Gating temperature for the Fig2protocol; no superconducting transition reported. Thermodynamic equilibrium is unverified in the checked provenance. | measurement; gate-application-temperature | Transport, XPS and isotope/SIMS controls | ambient; unknown GPa | unknown | experiment; [source](#ref-source-cd5c2b85b8e3a53c) |\n| WTe2 (aliases: tungsten ditelluride, Sajadi M1); Sajadi M1 reference for the characteristic half-resistance temperature | 1 K; 1 K is the resistance normalization reference for T1/2; it is not a transition temperature. No new numerical Tc is extracted. Thermodynamic equilibrium remains unverified. | normal-state; normal-resistance-reference | Four-terminal resistance reference | ambient; unknown GPa | unknown | experiment; [source](#ref-source-e8160470a5b03301) |"}],"markdown":"# Electrostatic gating: charge control and chemical changes\n\nRead gate-tuned superconductivity through device history, capacitance, chemical controls and the actual transition criterion.\n\n## Scope\n\nGating specifies an applied-voltage protocol, not its microscopic mechanism. A solid dielectric can accumulate interfacial charge; an electrolyte can also change oxygen content, drive redox or move ions. Whether a particular experiment is predominantly electrostatic requires evidence about the actual material, temperature, time and voltage history. Reversible resistance alone is insufficient: Jeong's VO2 study demonstrated reversible conductance switching associated with oxygen-vacancy formation. That experiment is a mechanism control, not a superconducting discovery. [R8](#ref-source-cd5c2b85b8e3a53c)\n\nKeep the early platforms separate. Ueno and colleagues reported gated SrTiO3 in a paper published online on 12 October 2008. Ye and colleagues reported ZrNCl with a transition temperature of 15.2 K; that paper appeared online on 22 November 2009 and in the February 2010 issue. The online and issue dates describe one ZrNCl paper, not separate discoveries. The accessible author-institution records support the material and attribution; the checked ZrNCl abstract does not specify an onset, midpoint or zero-resistance criterion. No exact SrTiO3 transition temperature or common criterion is assigned from these limited records. [R2](#ref-source-3c6933981eaa417d) [R3](#ref-source-831c3a9c5619ac1d)\n\n## Mathematical assumptions\n\nFor a uniform planar device with constant areal capacitance $C_A$, an electron-accumulation convention gives $\\Delta n_{2D}=C_A\\Delta V/e$, where $e>0$. If the measured total differential capacitance $C(V)=dQ/dV$ varies with voltage, use $\\Delta n_{2D}=(Ae)^{-1}\\int C(V)\\,dV$ for gated area $A$. Multiplying the endpoint capacitance by the entire voltage interval is generally wrong. Caviglia explicitly integrated the nonlinear response of the SrTiO3 dielectric. [R1](#ref-source-e9e3a49b753191bc)\n\nIn a simple positive-capacitance model, $C_A^{-1}=C_{g,A}^{-1}+C_{q,A}^{-1}$ accounts for geometric and quantum capacitances in series, with $C_{q,A}=e^2\\partial n_{2D}/\\partial\\mu$. Traps, leakage, negative compressibility and spatially nonuniform channels require a richer treatment. For two gates, the ideal charge estimate is $en_{2D}=C_{t,A}(V_t-V_{t0})+C_{b,A}(V_b-V_{b0})$. Offset voltages and dielectric calibration are assumptions to report, not quantities fixed by the formula. [R1](#ref-source-e9e3a49b753191bc) [R6](#ref-source-117f1ab64b772ff1) [R7](#ref-source-e8160470a5b03301)\n\nSajadi calls the gate-derived quantity a doping density, not a measured mobile-carrier density: correlations and edge conduction complicate that identification. The author's supplementary Table 1 uses AFM thicknesses and assumed relative permittivities of 4 for hBN and 3.9 for SiO2 to calculate geometric areal capacitances:\n\n| Device and gate | Dielectric stack | Calculated capacitance (nF/cm²) |\n| --- | --- | --- |\n| M1 top | 5.8 nm hBN | 611 |\n| M1 bottom | 18 nm hBN + 285 nm SiO2 | 11.4 |\n| M2 top | 8 nm hBN | 443 |\n| M2 bottom | 29 nm hBN | 122 |\n\nIn a uniform planar model, the layers in M1's bottom dielectric are in series. Omitting its SiO2 layer would overestimate that capacitance by about 17 times. This is a local calculation from rounded source inputs, not an experimental recalibration. The geometric approximation does not include every quantum-capacitance, contact-screening or trapping effect.\n\nEven a fixed estimated density does not specify both gate voltages: with constant capacitances, $c_t\\Delta V_t+c_b\\Delta V_b=0$ leaves the voltage-weighted sum unchanged while their difference changes. This identity does not demonstrate an unchanged transverse field, current path or superconducting state. Similarly, $Q=\\int I_gdt$ is transferred charge, without assigning its partition among the channel, traps and chemical reactions. Geometry arithmetic does not measure mobile carriers. [R7](#ref-source-e8160470a5b03301) [R8](#ref-source-cd5c2b85b8e3a53c)\n\n## Experimental criteria\n\nCaviglia's LaAlO3/SrTiO3 device used the substrate as a back-gate dielectric. Its capacitance depended on sweep history; conditioning at the highest positive voltage produced reproducible sweeps, and the resulting zero-voltage state was not the as-grown state. The superconducting dome used temperatures extracted from a BKT resistance model, reaching approximately 0.310 K. The 0.400 K normal-state resistance and 1.5 K capacitance measurements are separate observables. Preserve the fit model and preparation history when comparing this dome with other systems. [R1](#ref-source-e9e3a49b753191bc)\n\nFatemi's monolayer WTe2 device 1 illustrates why one transition has several temperatures. At bottom/top gate voltages 4/5 V, resistance reached 90% of its normal value near 0.820 K, 50% near 0.580 K and zero near 0.350 K. Device 2 reached a midpoint near 0.950 K but retained residual resistance attributed to a device imperfection. The two devices and criteria must not be collapsed into “zero resistance at 1 K.” Their Hall and capacitance estimates broadly agreed, with low-density deviations discussed as possibly inhomogeneous transport. [R6](#ref-source-117f1ab64b772ff1)\n\nMoS2 provides a related criterion warning. Ye established a gate-controlled dome in a band insulator. In Lu's later author manuscript, the phase-diagram panel uses 90% of the normal resistance at 15 K, whereas the remaining analysis uses 50%. A corresponding low-temperature state is labeled 2.63 K by the former criterion and 2.37 K by the latter. Keep those labels distinct from BKT temperatures or high-field boundaries. The layer-localization and spin–orbit interpretation also depends on the device model and field orientation. [R4](#ref-source-e8b9a66d143832fb) [R5](#ref-source-cba51ab2111ccf0a)\n\nSajadi's M1 device uses the characteristic temperature $T_{1/2}$ where the measured resistance reaches half its value at 1 K. The 1 K reference is not $T_c$. Supplementary section S8 explicitly distinguishes characteristic parameters from precise critical parameters; gradual transitions and limited contact arrangements constrain their interpretation. Different fractions of the normal resistance produce different characteristic fields and derived lengths.\n\nAt 20 mK, M1 reaches a roughly 0.3 ohm experimental noise floor for the reported gate-derived density above $7\\times10^{12}\\,\\mathrm{cm}^{-2}$. This is finite measurement sensitivity under specified conditions, not exact mathematical zero or a transition at 20 mK. Its sheet-resistivity estimate additionally assumes that current spreads little outside a chosen rectangle, with width/length about 10. A four-terminal resistance does not remove uncertainty in that current path. No new numerical $T_c$ or thermodynamic phase boundary is extracted here. [R7](#ref-source-e8160470a5b03301)\n\n## Limits and disputes\n\nJeong's VO2 evidence went beyond reversible transport: conductance persisted after the ionic liquid was removed, vanadium core-level spectra changed, and reverse gating in oxygen-18 produced an isotope depth profile measured by secondary-ion mass spectrometry. Ungated regions receiving the same isotope exposure served as controls. These results support chemical modification in those devices; they do not prove that every ionic-liquid-gated superconductor follows the same mechanism. Full supplementary procedures and quantitative vacancy reconstruction remain outside this scoped review. [R8](#ref-source-cd5c2b85b8e3a53c)\n\nA useful electrostatic interpretation therefore compares leakage and dwell-time behavior, sweep recovery, independent charge estimates, thickness dependence and before/after structural or chemical evidence. No single low-leakage threshold or unchanged spectrum proves the absence of all reactions. State the sensitivity and spatial sampling of each control. Conversely, hysteresis can arise from trapping in a dielectric and is not by itself proof of electrochemistry. [R1](#ref-source-e9e3a49b753191bc) [R8](#ref-source-cd5c2b85b8e3a53c)\n\nA gate-induced dome does not uniquely identify a pairing mechanism or a quantum critical point. Strong in-plane critical fields require analysis of orbital geometry, spin–orbit coupling and the chosen resistive threshold; they do not automatically establish triplet pairing. Switching a quantum spin Hall material into a superconducting regime creates an opportunity to investigate topology, but does not by itself demonstrate a topological superconducting gap or Majorana modes. [R4](#ref-source-e8b9a66d143832fb) [R5](#ref-source-cba51ab2111ccf0a) [R6](#ref-source-117f1ab64b772ff1) [R7](#ref-source-e8160470a5b03301)\n\n## Discovery implications\n\nTreat the device and voltage history as part of the material record: dielectric or electrolyte, thickness, gate geometry, charging temperature, dwell time, leakage, reset protocol and independent carrier estimate. Separate superconducting onset, midpoint, measured zero and model-extracted BKT temperatures. Use chemistry-sensitive controls to decide whether a changed state belongs under electrostatic tuning or compositional modification. The source-linked records below preserve reported observations and explicit unknowns; they are not a ranking of intrinsic material performance. These records use unknown for equilibrium because their checked provenance does not establish a thermodynamic equilibrium state; this is not evidence of nonequilibrium. [R1](#ref-source-e9e3a49b753191bc) [R5](#ref-source-cba51ab2111ccf0a) [R6](#ref-source-117f1ab64b772ff1) [R8](#ref-source-cd5c2b85b8e3a53c)\n\n## Related topics\n\nContinue with [chemical doping](/scwiki/chemical-doping), [zero resistance](/scwiki/zero-resistance), [critical fields](/scwiki/critical-fields), [two-dimensional superconductivity](/scwiki/two-dimensional-interfaces) and [topological superconductivity](/scwiki/topological-superconductivity).\n\n## Material cases\n\nValues describe individual reports, not a ranking. Unknown means the checked source did not supply the field at this review scope.\n\n| Material and sample | Reported temperature | Criterion | Probe | Pressure | State | Evidence |\n|---|---|---|---|---|---|---|\n| LaAlO3/SrTiO3; Caviglia gate-tuned dome maximum | 0.31 K; Approximate maximum from a BKT fit; not an onset or measured-zero temperature. Thermodynamic equilibrium is unverified in the checked provenance. | transition; BKT-resistance-fit | Four-point sheet resistance | ambient; unknown GPa | unknown | experiment; [source](#ref-source-e9e3a49b753191bc) |\n| WTe2 (aliases: tungsten ditelluride); Fatemi device1 Vbg4V/Vtg5V | 0.82 K; Approximate onset at90percent normal resistance; same device transition has lower midpoint and zero. Thermodynamic equilibrium is unverified in the checked provenance. | transition; resistance-90-percent-normal | Four-probe resistance | ambient; unknown GPa | unknown | experiment; [source](#ref-source-117f1ab64b772ff1) |\n| WTe2 (aliases: tungsten ditelluride); Fatemi device1 Vbg4V/Vtg5V | 0.58 K; Approximate midpoint, distinct from onset and zero. Thermodynamic equilibrium is unverified in the checked provenance. | transition; resistance-50-percent-normal | Four-probe resistance | ambient; unknown GPa | unknown | experiment; [source](#ref-source-117f1ab64b772ff1) |\n| WTe2 (aliases: tungsten ditelluride); Fatemi device1 Vbg4V/Vtg5V | 0.35 K; Approximate measured zero; not mathematical proof of zero uncertainty. Thermodynamic equilibrium is unverified in the checked provenance. | transition; zero-resistance | Four-probe resistance | ambient; unknown GPa | unknown | experiment; [source](#ref-source-117f1ab64b772ff1) |\n| WTe2 (aliases: tungsten ditelluride); Fatemi device2 maximum midpoint | 0.95 K; Residual resistance persists due to reported device imperfection; not zero-resistance at0.95K. Thermodynamic equilibrium is unverified in the checked provenance. | transition; resistance-50-percent-normal | Four-probe resistance | ambient; unknown GPa | unknown | experiment; [source](#ref-source-117f1ab64b772ff1) |\n| MoS2 (aliases: molybdenum disulfide); Lu D1 low-temperature state; authorv2 Fig1D | 2.63 K; Phase-diagram criterion relative to normal resistance at15K; same state midpoint2.37K. Thermodynamic equilibrium is unverified in the checked provenance. | transition; resistance-90-percent-normal | Gate-induced sheet resistance | ambient; unknown GPa | unknown | experiment; [source](#ref-source-cba51ab2111ccf0a) |\n| MoS2 (aliases: molybdenum disulfide); Lu D1 low-temperature state; authorv2 Fig1E | 2.37 K; Midpoint criterion used for subsequent field analysis; not the90percent phase-diagram label. Thermodynamic equilibrium is unverified in the checked provenance. | transition; resistance-50-percent-normal | Gate-induced sheet resistance | ambient; unknown GPa | unknown | experiment; [source](#ref-source-cba51ab2111ccf0a) |\n| ZrNCl; Ye liquid-gated atomically flat film | 15.2 K; Exact onset/midpoint/zero criterion not independently reviewed. Not Ueno2008SrTiO3. Thermodynamic equilibrium is unverified in the checked provenance. | transition; transition-unspecified | Field-induced superconductivity; abstract-level evidence | ambient; unknown GPa | unknown | experiment; [source](#ref-source-831c3a9c5619ac1d) |\n| WTe2 (aliases: tungsten ditelluride, Sajadi M1); Sajadi M1 author v1; gate-derived doping above 7e12 cm^-2 | 0.02 K; At 20 mK, M1 reaches an approximately 0.3 ohm noise floor for gate-derived doping above 7 × 10^12 cm^-2. This is finite sensitivity, not exact zero or a 20 mK transition. Density is capacitance-derived, not an independent mobile-carrier measurement. Thermodynamic equilibrium remains unverified. | measurement; resistance-noise-floor-observation | Four-terminal differential resistance | ambient; unknown GPa | unknown | experiment; [source](#ref-source-e8160470a5b03301) |\n| MoS2 (aliases: molybdenum disulfide); Lu normal resistance reference | 15 K; Normalization reference used in the90percent criterion, not superconducting Tc. Thermodynamic equilibrium is unverified in the checked provenance. | normal-state; normal-resistance-reference | Sheet resistance | ambient; unknown GPa | unknown | experiment; [source](#ref-source-cba51ab2111ccf0a) |\n| VO2; Jeong reversible-gating chemical control | 300 K; Gating temperature for the Fig2protocol; no superconducting transition reported. Thermodynamic equilibrium is unverified in the checked provenance. | measurement; gate-application-temperature | Transport, XPS and isotope/SIMS controls | ambient; unknown GPa | unknown | experiment; [source](#ref-source-cd5c2b85b8e3a53c) |\n| WTe2 (aliases: tungsten ditelluride, Sajadi M1); Sajadi M1 reference for the characteristic half-resistance temperature | 1 K; 1 K is the resistance normalization reference for T1/2; it is not a transition temperature. No new numerical Tc is extracted. Thermodynamic equilibrium remains unverified. | normal-state; normal-resistance-reference | Four-terminal resistance reference | ambient; unknown GPa | unknown | experiment; [source](#ref-source-e8160470a5b03301) |\n\n## Sources\n\n### Ref source-e9e3a49b753191bc\n\n[R1] Electric field control of the LaAlO3/SrTiO3 interface ground state (2008). [DOI 10.1038/nature07576](https://doi.org/10.1038/nature07576). Publication: journal-article. Check: selected-author-capacitance-history-and-BKT. Checked: 2026-10-18. Author v1 submitted 3 July 2008; journal issue 4 December 2008. Selected pp. 3–8 and notes pp. 10–11 read; Fig. 3 p. 6 visually checked. Nonlinear capacitance integration, conditioning, BKT fit and normal-state temperatures retained. Final-version comparison and raw-data fits remain open.\n### Ref source-3c6933981eaa417d\n\n[R2] Electric-field-induced superconductivity in an insulator (2008). [DOI 10.1038/nmat2298](https://doi.org/10.1038/nmat2298). Publication: journal-article. Check: publisher-identity-and-author-institute-summary. Checked: 2026-10-20. Published online 12 October 2008. Publisher metadata and authors institute summary identify SrTiO3, not ZrNCl. Original full methods and transition criterion were not read; no exact Tc is assigned here. Publisher dates and author-institution records rechecked; full text remains unavailable at checked official endpoints. No expanded transition-criterion claim.\n### Ref source-831c3a9c5619ac1d\n\n[R3] Liquid-gated interface superconductivity on an atomically flat film (2010). [DOI 10.1038/nmat2587](https://doi.org/10.1038/nmat2587). Publication: journal-article. Check: author-institution-abstract-and-publisher-dates. Checked: 2026-10-20. Ye et al.; online 22 November 2009, issue February 2010. Authors institutional abstract identifies ZrNCl and 15.2 K; publisher confirms dates. Full methods and exact onset/midpoint/zero criterion not reviewed. Publisher dates and author-institution records rechecked; full text remains unavailable at checked official endpoints. No expanded transition-criterion claim.\n### Ref source-e8b9a66d143832fb\n\n[R4] Superconducting Dome in a Gate-Tuned Band Insulator (2012). [DOI 10.1126/science.1228006](https://doi.org/10.1126/science.1228006). Publication: journal-article. Check: author-institution-abstract-only. Checked: 2026-10-18. Published 30 November 2012. Authors institutional abstract supports a MoS2 dome using liquid and solid gating. Final PDF is embargoed there; full methods and raw data were not read.\n### Ref source-cba51ab2111ccf0a\n\n[R5] Evidence for two-dimensional Ising superconductivity in gated MoS2 (2015). [DOI 10.1126/science.aab2277](https://doi.org/10.1126/science.aab2277). Publication: journal-article. Check: selected-author-v2-criteria-and-figure. Checked: 2026-10-18. Author v2 submitted 5 August 2015; Science 350, 1353–1357. Selected v1 p. 3 and captions pp. 11–12, v2 captions pp. 11–13 and Fig. 1 p. 17 checked visually. Distinct 90%/50% criteria and model context retained; no complete spin-orbit derivation, supplement, final-version comparison or raw-data fit.\n### Ref source-117f1ab64b772ff1\n\n[R6] Electrically tunable low-density superconductivity in a monolayer topological insulator (2018). [DOI 10.1126/science.aar4642](https://doi.org/10.1126/science.aar4642). Publication: journal-article. Check: selected-final-journal-device-and-transition-criteria. Checked: 2026-10-18. Online 25 October 2018; issue 23 November. Selected final journal pp. 1–3 read; p. 2 Figs. 1–2 visually checked. Device-specific thresholds and capacitance/Hall limits retained. Supplement, raw data and topological-gap verification not reviewed.\n### Ref source-e8160470a5b03301\n\n[R7] Gate-induced superconductivity in a monolayer topological insulator (2018). [DOI 10.1126/science.aar4426](https://doi.org/10.1126/science.aar4426). Publication: journal-article. Check: selected-author-density-definition-device-geometry-and-criteria. Checked: 2026-10-20. Author v1 submitted 12 September 2018; journal online 25 October, issue 23 November. Selected pp. 2–4, S1/Table 1 pp. 9–10 and S8 p. 17 read; pp. 2, 3, 10 and 17 visually inspected. Geometric estimates, two device stacks, half-R(1 K), the finite 0.3 ohm floor at 20 mK and assumed current geometry remain distinct. Local series-capacitance arithmetic is not a carrier measurement. Complete supplement, raw-data reconstruction and final-version equivalence remain unchecked.\n### Ref source-cd5c2b85b8e3a53c\n\n[R8] Suppression of Metal-Insulator Transition in VO2 by Electric Field–Induced Oxygen Vacancy Formation (2013). [DOI 10.1126/science.1230512](https://doi.org/10.1126/science.1230512). Publication: journal-article. Check: selected-final-journal-chemical-controls. Checked: 2026-10-18. Published 22 March 2013. Selected PDF pp. 2–4 (journal pp. 1402–1404) and p. 3 Figs. 2–3 visually checked: reversible transport, liquid removal, XPS, isotope/SIMS controls and oxygen dependence. Full supplement and vacancy quantification not reviewed. This is not a superconducting Tc report.\n\n## Claim evidence and conditions\n\n### scwiki-e3-claim-scope-1\n\nGating specifies an applied-voltage protocol, not its microscopic mechanism. A solid dielectric can accumulate interfacial charge; an electrolyte can also change oxygen content, drive redox or move ions. Whether a particular experiment is predominantly electrostatic requires evidence about the actual material, temperature, time and voltage history. Reversible resistance alone is insufficient: Jeong's VO2 study demonstrated reversible conductance switching associated with oxygen-vacancy formation. That experiment is a mechanism control, not a superconducting discovery.\n\nEvidence: experiment. Sources: source-cd5c2b85b8e3a53c.\n\nConditions: Gate history, device, capacitance convention, temperature reference, transport threshold and chemical controls remain distinct. A gated topological insulator is not automatically a topological superconductor.\n\nVerification scope: Selected original passages and figures, explicit limited abstracts and bounded circuit algebra; complete scientific acceptance remains open.\n\n### scwiki-e3-claim-scope-2\n\nKeep the early platforms separate. Ueno and colleagues reported gated SrTiO3 in a paper published online on 12 October 2008. Ye and colleagues reported ZrNCl with a transition temperature of 15.2 K; that paper appeared online on 22 November 2009 and in the February 2010 issue. The online and issue dates describe one ZrNCl paper, not separate discoveries. The accessible author-institution records support the material and attribution; the checked ZrNCl abstract does not specify an onset, midpoint or zero-resistance criterion. No exact SrTiO3 transition temperature or common criterion is assigned from these limited records.\n\nEvidence: editorial-analysis. Sources: source-3c6933981eaa417d, source-831c3a9c5619ac1d.\n\nSource relationship: context-for-editorial-analysis. Comparison of publisher bibliographic dates and author-institution material/abstract records. Full Ueno/Ye transition methods remain unreviewed.\n\nConditions: Keep device M1/M2, gate geometry, assumed permittivity, estimated doping, temperature reference, resistance criterion and detection limit separate. No mobile-carrier measurement inferred from electrostatic arithmetic.\n\nVerification scope: Selected author v1 pp.2–4, S1/Table1 pp.9–10 and S8 p.17; pp.2/3/10/17 visually inspected where applicable. Ueno/Ye remain publisher/author-institution bibliographic and summary scope. No complete supplement, final comparison or raw-data fit.\n\n### scwiki-e3-claim-mathematical-assumptions-1\n\nFor a uniform planar device with constant areal capacitance $C_A$, an electron-accumulation convention gives $\\Delta n_{2D}=C_A\\Delta V/e$, where $e>0$. If the measured total differential capacitance $C(V)=dQ/dV$ varies with voltage, use $\\Delta n_{2D}=(Ae)^{-1}\\int C(V)\\,dV$ for gated area $A$. Multiplying the endpoint capacitance by the entire voltage interval is generally wrong. Caviglia explicitly integrated the nonlinear response of the SrTiO3 dielectric.\n\nEvidence: theory. Sources: source-e9e3a49b753191bc.\n\nSource relationship: mixed-source-and-local-derivation. Source experiments motivate the geometry and capacitance conditions. Displayed ideal circuit identities and unit conversions are local illustrative derivations, not source-measured carrier counts.\n\nConditions: Gate history, device, capacitance convention, temperature reference, transport threshold and chemical controls remain distinct. A gated topological insulator is not automatically a topological superconductor.\n\nVerification scope: Selected original passages and figures, explicit limited abstracts and bounded circuit algebra; complete scientific acceptance remains open.\n\n### scwiki-e3-claim-mathematical-assumptions-2\n\nIn a simple positive-capacitance model, $C_A^{-1}=C_{g,A}^{-1}+C_{q,A}^{-1}$ accounts for geometric and quantum capacitances in series, with $C_{q,A}=e^2\\partial n_{2D}/\\partial\\mu$. Traps, leakage, negative compressibility and spatially nonuniform channels require a richer treatment. For two gates, the ideal charge estimate is $en_{2D}=C_{t,A}(V_t-V_{t0})+C_{b,A}(V_b-V_{b0})$. Offset voltages and dielectric calibration are assumptions to report, not quantities fixed by the formula.\n\nEvidence: theory. Sources: source-e9e3a49b753191bc, source-117f1ab64b772ff1, source-e8160470a5b03301.\n\nSource relationship: mixed-source-and-local-derivation. Source experiments motivate the geometry and capacitance conditions. Displayed ideal circuit identities and unit conversions are local illustrative derivations, not source-measured carrier counts.\n\nConditions: Gate history, device, capacitance convention, temperature reference, transport threshold and chemical controls remain distinct. A gated topological insulator is not automatically a topological superconductor.\n\nVerification scope: Selected original passages and figures, explicit limited abstracts and bounded circuit algebra; complete scientific acceptance remains open.\n\n### scwiki-e3-claim-mathematical-assumptions-3\n\nSajadi calls the gate-derived quantity a doping density, not a measured mobile-carrier density: correlations and edge conduction complicate that identification. The author's supplementary Table 1 uses AFM thicknesses and assumed relative permittivities of 4 for hBN and 3.9 for SiO2 to calculate geometric areal capacitances:\n\n| Device and gate | Dielectric stack | Calculated capacitance (nF/cm²) |\n| --- | --- | --- |\n| M1 top | 5.8 nm hBN | 611 |\n| M1 bottom | 18 nm hBN + 285 nm SiO2 | 11.4 |\n| M2 top | 8 nm hBN | 443 |\n| M2 bottom | 29 nm hBN | 122 |\n\nIn a uniform planar model, the layers in M1's bottom dielectric are in series. Omitting its SiO2 layer would overestimate that capacitance by about 17 times. This is a local calculation from rounded source inputs, not an experimental recalibration. The geometric approximation does not include every quantum-capacitance, contact-screening or trapping effect.\n\nEven a fixed estimated density does not specify both gate voltages: with constant capacitances, $c_t\\Delta V_t+c_b\\Delta V_b=0$ leaves the voltage-weighted sum unchanged while their difference changes. This identity does not demonstrate an unchanged transverse field, current path or superconducting state. Similarly, $Q=\\int I_gdt$ is transferred charge, without assigning its partition among the channel, traps and chemical reactions. Geometry arithmetic does not measure mobile carriers.\n\nEvidence: theory. Sources: source-e8160470a5b03301, source-cd5c2b85b8e3a53c.\n\nSource relationship: mixed-source-and-local-derivation. Sajadi author v1 pp.2–3 and S1/Table1 supply definitions and geometric inputs. Series reconstruction and equal weighted-charge identities are local model checks; gate-current partition is an editorial inference limit informed by Jeong chemical controls.\n\nConditions: Keep device M1/M2, gate geometry, assumed permittivity, estimated doping, temperature reference, resistance criterion and detection limit separate. No mobile-carrier measurement inferred from electrostatic arithmetic.\n\nVerification scope: Selected author v1 pp.2–4, S1/Table1 pp.9–10 and S8 p.17; pp.2/3/10/17 visually inspected where applicable. Ueno/Ye remain publisher/author-institution bibliographic and summary scope. No complete supplement, final comparison or raw-data fit.\n\n### scwiki-e3-claim-experimental-criteria-1\n\nCaviglia's LaAlO3/SrTiO3 device used the substrate as a back-gate dielectric. Its capacitance depended on sweep history; conditioning at the highest positive voltage produced reproducible sweeps, and the resulting zero-voltage state was not the as-grown state. The superconducting dome used temperatures extracted from a BKT resistance model, reaching approximately 0.310 K. The 0.400 K normal-state resistance and 1.5 K capacitance measurements are separate observables. Preserve the fit model and preparation history when comparing this dome with other systems.\n\nEvidence: experiment. Sources: source-e9e3a49b753191bc.\n\nConditions: Gate history, device, capacitance convention, temperature reference, transport threshold and chemical controls remain distinct. A gated topological insulator is not automatically a topological superconductor.\n\nVerification scope: Selected original passages and figures, explicit limited abstracts and bounded circuit algebra; complete scientific acceptance remains open.\n\n### scwiki-e3-claim-experimental-criteria-2\n\nFatemi's monolayer WTe2 device 1 illustrates why one transition has several temperatures. At bottom/top gate voltages 4/5 V, resistance reached 90% of its normal value near 0.820 K, 50% near 0.580 K and zero near 0.350 K. Device 2 reached a midpoint near 0.950 K but retained residual resistance attributed to a device imperfection. The two devices and criteria must not be collapsed into “zero resistance at 1 K.” Their Hall and capacitance estimates broadly agreed, with low-density deviations discussed as possibly inhomogeneous transport.\n\nEvidence: experiment. Sources: source-117f1ab64b772ff1.\n\nConditions: Gate history, device, capacitance convention, temperature reference, transport threshold and chemical controls remain distinct. A gated topological insulator is not automatically a topological superconductor.\n\nVerification scope: Selected original passages and figures, explicit limited abstracts and bounded circuit algebra; complete scientific acceptance remains open.\n\n### scwiki-e3-claim-experimental-criteria-3\n\nMoS2 provides a related criterion warning. Ye established a gate-controlled dome in a band insulator. In Lu's later author manuscript, the phase-diagram panel uses 90% of the normal resistance at 15 K, whereas the remaining analysis uses 50%. A corresponding low-temperature state is labeled 2.63 K by the former criterion and 2.37 K by the latter. Keep those labels distinct from BKT temperatures or high-field boundaries. The layer-localization and spin–orbit interpretation also depends on the device model and field orientation.\n\nEvidence: experiment. Sources: source-e8b9a66d143832fb, source-cba51ab2111ccf0a.\n\nConditions: Gate history, device, capacitance convention, temperature reference, transport threshold and chemical controls remain distinct. A gated topological insulator is not automatically a topological superconductor.\n\nVerification scope: Selected original passages and figures, explicit limited abstracts and bounded circuit algebra; complete scientific acceptance remains open.\n\n### scwiki-e3-claim-experimental-criteria-4\n\nSajadi's M1 device uses the characteristic temperature $T_{1/2}$ where the measured resistance reaches half its value at 1 K. The 1 K reference is not $T_c$. Supplementary section S8 explicitly distinguishes characteristic parameters from precise critical parameters; gradual transitions and limited contact arrangements constrain their interpretation. Different fractions of the normal resistance produce different characteristic fields and derived lengths.\n\nAt 20 mK, M1 reaches a roughly 0.3 ohm experimental noise floor for the reported gate-derived density above $7\\times10^{12}\\,\\mathrm{cm}^{-2}$. This is finite measurement sensitivity under specified conditions, not exact mathematical zero or a transition at 20 mK. Its sheet-resistivity estimate additionally assumes that current spreads little outside a chosen rectangle, with width/length about 10. A four-terminal resistance does not remove uncertainty in that current path. No new numerical $T_c$ or thermodynamic phase boundary is extracted here.\n\nEvidence: experiment. Sources: source-e8160470a5b03301.\n\nSource relationship: direct-support. Sajadi author v1 p.3 and selected S1/S8 passages distinguish a characteristic resistance threshold, finite measurement floor and assumed current geometry.\n\nConditions: Keep device M1/M2, gate geometry, assumed permittivity, estimated doping, temperature reference, resistance criterion and detection limit separate. No mobile-carrier measurement inferred from electrostatic arithmetic.\n\nVerification scope: Selected author v1 pp.2–4, S1/Table1 pp.9–10 and S8 p.17; pp.2/3/10/17 visually inspected where applicable. Ueno/Ye remain publisher/author-institution bibliographic and summary scope. No complete supplement, final comparison or raw-data fit.\n\n### scwiki-e3-claim-limits-and-disputes-1\n\nJeong's VO2 evidence went beyond reversible transport: conductance persisted after the ionic liquid was removed, vanadium core-level spectra changed, and reverse gating in oxygen-18 produced an isotope depth profile measured by secondary-ion mass spectrometry. Ungated regions receiving the same isotope exposure served as controls. These results support chemical modification in those devices; they do not prove that every ionic-liquid-gated superconductor follows the same mechanism. Full supplementary procedures and quantitative vacancy reconstruction remain outside this scoped review.\n\nEvidence: experiment. Sources: source-cd5c2b85b8e3a53c.\n\nConditions: Gate history, device, capacitance convention, temperature reference, transport threshold and chemical controls remain distinct. A gated topological insulator is not automatically a topological superconductor.\n\nVerification scope: Selected original passages and figures, explicit limited abstracts and bounded circuit algebra; complete scientific acceptance remains open.\n\n### scwiki-e3-claim-limits-and-disputes-2\n\nA useful electrostatic interpretation therefore compares leakage and dwell-time behavior, sweep recovery, independent charge estimates, thickness dependence and before/after structural or chemical evidence. No single low-leakage threshold or unchanged spectrum proves the absence of all reactions. State the sensitivity and spatial sampling of each control. Conversely, hysteresis can arise from trapping in a dielectric and is not by itself proof of electrochemistry.\n\nEvidence: experiment. Sources: source-e9e3a49b753191bc, source-cd5c2b85b8e3a53c.\n\nConditions: Gate history, device, capacitance convention, temperature reference, transport threshold and chemical controls remain distinct. A gated topological insulator is not automatically a topological superconductor.\n\nVerification scope: Selected original passages and figures, explicit limited abstracts and bounded circuit algebra; complete scientific acceptance remains open.\n\n### scwiki-e3-claim-limits-and-disputes-3\n\nA gate-induced dome does not uniquely identify a pairing mechanism or a quantum critical point. Strong in-plane critical fields require analysis of orbital geometry, spin–orbit coupling and the chosen resistive threshold; they do not automatically establish triplet pairing. Switching a quantum spin Hall material into a superconducting regime creates an opportunity to investigate topology, but does not by itself demonstrate a topological superconducting gap or Majorana modes.\n\nEvidence: experiment. Sources: source-e8b9a66d143832fb, source-cba51ab2111ccf0a, source-117f1ab64b772ff1, source-e8160470a5b03301.\n\nConditions: Gate history, device, capacitance convention, temperature reference, transport threshold and chemical controls remain distinct. A gated topological insulator is not automatically a topological superconductor.\n\nVerification scope: Selected original passages and figures, explicit limited abstracts and bounded circuit algebra; complete scientific acceptance remains open.\n\n### scwiki-e3-claim-discovery-implications-1\n\nTreat the device and voltage history as part of the material record: dielectric or electrolyte, thickness, gate geometry, charging temperature, dwell time, leakage, reset protocol and independent carrier estimate. Separate superconducting onset, midpoint, measured zero and model-extracted BKT temperatures. Use chemistry-sensitive controls to decide whether a changed state belongs under electrostatic tuning or compositional modification. The source-linked records below preserve reported observations and explicit unknowns; they are not a ranking of intrinsic material performance. These records use unknown for equilibrium because their checked provenance does not establish a thermodynamic equilibrium state; this is not evidence of nonequilibrium.\n\nEvidence: editorial-analysis. Sources: source-e9e3a49b753191bc, source-cba51ab2111ccf0a, source-117f1ab64b772ff1, source-cd5c2b85b8e3a53c.\n\nSource relationship: context-for-editorial-analysis. Editorial comparison of device/probe requirements; no synthesis ranking or equilibrium certification.\n\nConditions: Gate history, device, capacitance convention, temperature reference, transport threshold and chemical controls remain distinct. A gated topological insulator is not automatically a topological superconductor.\n\nVerification scope: Selected original passages and figures, explicit limited abstracts and bounded circuit algebra; complete scientific acceptance remains open.\n\n## Revision and review\n\nArticle ID: scwiki-e3. Revision: 44a94ba4b79eef5b0a68. Updated: 2026-10-19T18:33:48.941677+00:00.\n\nReview scope: Selected Caviglia, Lu and Sajadi author passages; Fatemi and Jeong final-journal passages and figures; limited Ueno and Ye source checks; bounded capacitance algebra. Follow-up: Sajadi S1 device geometry and S8 characteristic-criterion passages; source attribution/dates rechecked; local series-capacitance model comparison.\n\n- Complete scientific acceptance, full supplements, remaining final-version comparisons and raw-data reproduction remain open.\n- Ueno identity and author summary do not supply a checked transition criterion; ZrNCl15.2K retains an unspecified criterion from an abstract.\n- Simple capacitance calculations do not establish mobile-carrier density or the absence of electrochemistry.\n- Device thresholds, BKT fits and normal-state reference temperatures cannot be treated as equivalent Tc values.\n- Selected supplementary sections do not constitute a complete supplement or independent scientific review. None of these records is certified thermodynamically equilibrated.\n\nSource: [E_tuning_parameters/E3_electrostatic_gating.md](https://github.com/JackZH26/jzis-superconductivity/blob/0a7c9d6696804ec26aa12f8eed68b55c9b3c0fcf/E_tuning_parameters/E3_electrostatic_gating.md), commit 0a7c9d6696804ec26aa12f8eed68b55c9b3c0fcf, SHA-256 d2e5458129cccb307c7914380872fd66475978d4d43cb2f8e3851c26b4ca6608.\n","wordCount":1235}}