{"schemaVersion":"1.0","revision":"fa961ab24277a91737c3","article":{"id":"scwiki-h1","topicId":"scwiki-topic-h1","code":"H1","slug":"strange-metals","title":"Strange metals and linear-temperature resistivity","summary":"Evaluate normal-state transport without conflating a fitted exponent, a relaxation time, quantum criticality and the superconducting mechanism.","aliases":["strange metal","strange metals","linear temperature resistivity","marginal Fermi liquid","奇异金属"],"evidenceTypes":["theory","experimental"],"relatedCodes":["A8","H2","B3"],"editorialStatus":"scoped-check","contentState":"pilot","modifiedAt":"2026-10-18T16:26:45.370525+00:00","review":{"checkedAt":"2026-10-19","scope":"Selected final Nd-LSCO methods and Figure 2, Romero author methods and Figure 3 with final abstract, inherited graphene evidence, primary abstracts and independent synthetic fit checks.","limitations":["Complete scientific acceptance remains open.","Full raw-data fits, wider competing literature and final-version comparisons remain incomplete.","Cooper evidence is abstract-level here; Varma erratum identity is recorded without claiming its contents were checked.","Synthetic exponents and fitting windows do not establish a microscopic mechanism or quantum critical point."]},"provenance":{"repository":"JackZH26/jzis-superconductivity","commit":"0a7c9d6696804ec26aa12f8eed68b55c9b3c0fcf","path":"H_anomalous_normal_state/H1_strange_metal_linear_T.md","sha256":"d5c5f605dcb2d5fe7ea2eb72ba5530c10f3938d54760cba6d33d9656651bfc39","sourceId":"file-4a97f55e37a842bb"},"references":[{"id":"source-a5d6480d08ee8555","doi":"10.1103/PhysRevB.41.846","title":"Normal-state transport properties of Bi2+xSr2-yCuO6+delta crystals","year":1990,"url":"https://doi.org/10.1103/PhysRevB.41.846","publicationStatus":"journal-article","verification":{"scope":"primary-abstract-scoped-check","checkedAt":"2026-10-18","evidenceUrl":"https://journals.aps.org/prb/abstract/10.1103/PhysRevB.41.846","note":"Publisher abstract only: anisotropic normal-state transport in Bi-based crystals. Full measurement protocol and numerical curves not checked."}},{"id":"source-1610fd228e679225","doi":"10.1126/science.1165015","title":"Anomalous Criticality in the Electrical Resistivity of La2-xSrxCuO4","year":2009,"url":"https://doi.org/10.1126/science.1165015","publicationStatus":"journal-article","verification":{"scope":"primary-abstract-and-publication-check","checkedAt":"2026-10-19","evidenceUrl":"https://pubmed.ncbi.nlm.nih.gov/19074310/","note":"Primary abstract reproduced by PubMed checked. Online 11 December 2008; issue 30 January 2009. Publisher full text was unavailable; numerical curves and measurement protocols remain unaudited here."}},{"id":"source-c1ae7869b672a8e8","doi":"10.1038/s41567-018-0334-2","title":"Universal T-linear resistivity and Planckian dissipation in overdoped cuprates","year":2019,"url":"https://doi.org/10.1038/s41567-018-0334-2","publicationStatus":"journal-article","verification":{"scope":"earlier-author-manuscript-scoped-check","checkedAt":"2026-10-18","evidenceUrl":"https://arxiv.org/pdf/1805.02512v1","note":"Selected v1 pp. 4, 7–8 and Figs. 1–2 captions: Drude assumptions, film method and magnetoresistance correction. Published volume year 2019; final-version comparison and complete data fitting remain open."}},{"id":"source-374c8bc13ced83e8","doi":"10.1038/s41586-021-03697-8","title":"Linear-in temperature resistivity from an isotropic Planckian scattering rate","year":2021,"url":"https://doi.org/10.1038/s41586-021-03697-8","publicationStatus":"journal-article","verification":{"scope":"selected-final-methods-results-and-figure-check","checkedAt":"2026-10-19","evidenceUrl":"https://warwick.ac.uk/fac/sci/physics/research/condensedmatt/supermag/pubs2021/Grissonnanche_Nature.595.667.2021.pdf","note":"Final results and selected methods read; printed page 669, Figure 2 visually checked. Compared selected author v2 passages. Temperature stability, absolute error, angular superconducting regions and fitted bandwidth distinguished. Complete fitting and raw-data reproduction remain open."}},{"id":"source-8135909144b6b16b","doi":"10.1103/PhysRevLett.124.076801","title":"Strange Metal in Magic-Angle Graphene with near Planckian Dissipation","year":2020,"url":"https://doi.org/10.1103/PhysRevLett.124.076801","publicationStatus":"journal-article","verification":{"scope":"primary-fulltext-scoped-check","checkedAt":"2026-10-18","evidenceUrl":"https://physics.aps.org/featured-article-pdf/10.1103/PhysRevLett.124.076801","note":"Selected published pp. 1–4, Fig. 1 and Eq. (1). Four-probe device, filling dependence and low-temperature SdH parameter assumptions checked; supplementary fits not reproduced."}},{"id":"source-05b2d5ff6757b5eb","doi":"10.1038/s41567-026-03266-8","title":"Planckian scattering and parallel conduction channels in an iron chalcogenide superconductor","year":2026,"url":"https://doi.org/10.1038/s41567-026-03266-8","publicationStatus":"journal-article","verification":{"scope":"selected-author-figure-and-final-abstract-check","checkedAt":"2026-10-19","evidenceUrl":"https://arxiv.org/pdf/2505.00623v1","note":"Author v1, 1 May 2025: selected methods and results, pages 1–4, read; page 4 Figure 3 visually checked. Final publisher abstract and publication date, 23 April 2026, checked. Final full text requires access; the attempted PDF returned HTML. Complete version comparison and spectral-weight calibration remain open."}},{"id":"source-5880a61b06ec84e6","doi":"10.1103/PhysRevLett.63.1996","title":"Phenomenology of the normal state of Cu-O high-temperature superconductors","year":1989,"url":"https://doi.org/10.1103/PhysRevLett.63.1996","publicationStatus":"journal-article","verification":{"scope":"publisher-abstract-check","checkedAt":"2026-10-19","evidenceUrl":"https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.63.1996","note":"Published 30 October 1989. Marginal-Fermi-liquid hypothesis checked at abstract level. The linked 1990 erratum is recorded separately; complete corrected derivation remains open."}},{"id":"source-2cdc898b9c5e504c","doi":"10.1103/PhysRevLett.64.497","title":"Erratum: Phenomenology of the normal state of Cu-O high-temperature superconductors","year":1990,"url":"https://doi.org/10.1103/PhysRevLett.64.497","publicationStatus":"journal-article","verification":{"scope":"publisher-erratum-identity-check","checkedAt":"2026-10-19","evidenceUrl":"https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.64.497","note":"Published 22 January 1990. Publisher linkage and identity verified. PDF endpoint returned 403; correction contents have not been independently read, so no corrected formula is attributed to it."}}],"claims":[{"id":"scwiki-h1-claim-scope-1","sectionId":"scope","statement":"A strange metal is identified through unusual normal-state behavior, often including resistivity approximately proportional to temperature after superconductivity is suppressed. It is an observational category, not a uniquely established microscopic phase or order parameter. The early Bi-based transport work and later overdoped-cuprate experiments concern particular specimens and temperature ranges. Their results do not provide a universal slope for all superconductors. Ordinary high-temperature electron–phonon transport can also be linear, so a room-temperature straight line alone is insufficient.","evidenceType":"hypothesis","sourceIds":["source-a5d6480d08ee8555","source-1610fd228e679225","source-374c8bc13ced83e8"],"conditions":"Fit window, residual subtraction, lifetime convention, angular superconducting exclusions and source version remain explicit.","verificationScope":"Selected primary texts and figures plus independent synthetic identifiability checks; full scientific acceptance remains open."},{"id":"scwiki-h1-claim-scope-2","sectionId":"scope","statement":"This article focuses on how observations constrain explanations. Linear resistivity, a transport relaxation rate near a thermal quantum scale, proximity to a quantum critical point and a high superconducting transition temperature are separate propositions. Each requires additional evidence. Even the identity of a relevant lifetime matters: a single-particle linewidth and a current-relaxation rate need not weight scattering processes in the same way.","evidenceType":"hypothesis","sourceIds":["source-c1ae7869b672a8e8","source-374c8bc13ced83e8","source-05b2d5ff6757b5eb"],"conditions":"Fit window, residual subtraction, lifetime convention, angular superconducting exclusions and source version remain explicit.","verificationScope":"Selected primary texts and figures plus independent synthetic identifiability checks; full scientific acceptance remains open."},{"id":"scwiki-h1-claim-mathematical-assumptions-1","sectionId":"mathematical-assumptions","statement":"For a fitted normal-state curve, write $\\rho(T)=\\rho_0+AT+BT^2$. This is an empirical decomposition over a stated interval; its terms do not automatically identify independent microscopic mechanisms. Define a local exponent relative to a trial residual $\\rho_r$ by $n_{\\mathrm{eff}}=d\\ln(\\rho-\\rho_r)/d\\ln T$, wherever the logarithm is defined. Derivatives amplify noise and depend on the residual subtraction. An exponent should therefore accompany its temperature window, uncertainty and treatment of the superconducting region.","evidenceType":"theory","sourceIds":["source-1610fd228e679225","source-c1ae7869b672a8e8"],"conditions":"Fit window, residual subtraction, lifetime convention, angular superconducting exclusions and source version remain explicit.","verificationScope":"Selected primary texts and figures plus independent synthetic identifiability checks; full scientific acceptance remains open."},{"id":"scwiki-h1-claim-mathematical-assumptions-2","sectionId":"mathematical-assumptions","statement":"An independent illustration uses exactly quadratic data, $\\rho=\\rho_0+BT^2$. If the trial residual differs by $\\epsilon=\\rho_r-\\rho_0$, then $n_{\\mathrm{eff}}=2BT^2/(BT^2-\\epsilon)$. One hundred and eight finite-difference checks verify this relation. With the correct residual, a positive mixture of linear and quadratic terms gives $n_{\\mathrm{eff}}=(A+2BT)/(A+BT)$, continuously between one and two; nine parameter cases confirm that limit. No abrupt phase boundary is required by this smooth crossover. These are synthetic checks, not fits to a paper's measurements.","evidenceType":"theory","sourceIds":["source-1610fd228e679225"],"conditions":"Fit window, residual subtraction, lifetime convention, angular superconducting exclusions and source version remain explicit.","verificationScope":"Selected primary texts and figures plus independent synthetic identifiability checks; full scientific acceptance remains open."},{"id":"scwiki-h1-claim-mathematical-assumptions-3","sectionId":"mathematical-assumptions","statement":"Two additional synthetic fits use $\\rho=10+0.1T^2$ in arbitrary consistent units. A best straight line over $9\\leq T\\leq11$ has maximum deviation below 0.4% of the mean resistivity; extending the interval to $1\\leq T\\leq20$ raises it above 20%. Thus apparent linearity over a narrow interval can hide curvature. These percentages depend on the chosen example and are not universal acceptance thresholds. Real analysis needs residual plots, independent temperature calibration and a measurement-specific noise model.","evidenceType":"theory","sourceIds":["source-1610fd228e679225"],"conditions":"Fit window, residual subtraction, lifetime convention, angular superconducting exclusions and source version remain explicit.","verificationScope":"Selected primary texts and figures plus independent synthetic identifiability checks; full scientific acceptance remains open."},{"id":"scwiki-h1-claim-mathematical-assumptions-4","sectionId":"mathematical-assumptions","statement":"For parallel conducting channels, conductivities add: $\\sigma_{\\mathrm{dc}}=\\sigma_0+S/\\Gamma$ in a specified Drude convention. If $S$ and $\\sigma_0$ are constant and $\\Gamma\\propto T$, the resulting resistivity is $\\rho=1/(a+b/T)$, which is generally nonlinear. Adding channel resistivities would describe a different circuit. Temperature-dependent spectral weight and finite frequency coverage must also be tested before assigning a lifetime from the total d.c. curve.","evidenceType":"theory","sourceIds":["source-05b2d5ff6757b5eb"],"conditions":"Fit window, residual subtraction, lifetime convention, angular superconducting exclusions and source version remain explicit.","verificationScope":"Selected primary texts and figures plus independent synthetic identifiability checks; full scientific acceptance remains open."},{"id":"scwiki-h1-claim-experimental-criteria-1","sectionId":"experimental-criteria","statement":"Grissonnanche and colleagues measured angle-dependent magnetoresistance in Nd-LSCO at hole concentration $p=0.24\\pm0.005$. The sample's zero-resistance transition is 11 K; the transport measurements use 45 T at 6, 12, 20 and 25 K. At the two lower temperatures, some field orientations still enter a superconducting region. A high field alone therefore does not certify that every angular data point is normal-state transport.","evidenceType":"experiment","sourceIds":["source-374c8bc13ced83e8"],"conditions":"Fit window, residual subtraction, lifetime convention, angular superconducting exclusions and source version remain explicit.","verificationScope":"Selected primary texts and figures plus independent synthetic identifiability checks; full scientific acceptance remains open."},{"id":"scwiki-h1-claim-experimental-criteria-2","sectionId":"experimental-criteria","statement":"Their fit separates a temperature-independent anisotropic contribution from an isotropic temperature-dependent rate, giving $\\alpha=1.2\\pm0.4$ in $\\hbar/\\tau_{\\mathrm{inel}}=\\alpha k_BT$. Total scattering is not isotropic. The analysis uses a bandwidth scale $160\\pm30$ meV constrained by specific heat and omits a low-temperature correction that could change it by about 20% at 6 K. Temperature stability of ±1 mK differs from absolute uncertainty of approximately ±1 K at 6 and 12 K. These qualifications belong with the extracted coefficient.","evidenceType":"experiment","sourceIds":["source-374c8bc13ced83e8"],"conditions":"Fit window, residual subtraction, lifetime convention, angular superconducting exclusions and source version remain explicit.","verificationScope":"Selected primary texts and figures plus independent synthetic identifiability checks; full scientific acceptance remains open."},{"id":"scwiki-h1-claim-experimental-criteria-3","sectionId":"experimental-criteria","statement":"Romero and colleagues resolve a narrower Drude channel and a broad background in two FeTe1−xSex films. The final abstract associates most condensate spectral weight with the narrower channel. In the checked author version, the scattering-rate fits use 20–40 K, and linewidths below the approximately 0.2 THz measurement limit cannot be resolved directly. Its frequency variable uses cycles per second, so $h$ appears in $\\Gamma=\\Gamma_0+\\alpha k_BT/h$; an angular-frequency rate instead uses $\\hbar$. A fitted spectral decomposition is stronger evidence than assigning a lifetime from total resistance alone, but it does not uniquely determine the pairing interaction.","evidenceType":"experiment","sourceIds":["source-05b2d5ff6757b5eb"],"conditions":"Fit window, residual subtraction, lifetime convention, angular superconducting exclusions and source version remain explicit.","verificationScope":"Selected primary texts and figures plus independent synthetic identifiability checks; full scientific acceptance remains open."},{"id":"scwiki-h1-claim-experimental-criteria-4","sectionId":"experimental-criteria","statement":"Cooper and colleagues report that a low-temperature linear contribution extends over a range of LSCO dopings and tracks superconductivity. The checked abstract supports that association, not a reanalysis of its numerical curves. Magic-angle graphene measurements provide another material setting with nearly linear transport; a similar temperature exponent across systems does not prove identical scattering or pairing mechanisms. Material geometry, filling and fit assumptions must accompany cross-system comparisons.","evidenceType":"experiment","sourceIds":["source-1610fd228e679225","source-8135909144b6b16b"],"conditions":"Fit window, residual subtraction, lifetime convention, angular superconducting exclusions and source version remain explicit.","verificationScope":"Selected primary texts and figures plus independent synthetic identifiability checks; full scientific acceptance remains open."},{"id":"scwiki-h1-claim-limits-and-disputes-1","sectionId":"limits-and-disputes","statement":"The marginal-Fermi-liquid proposal organizes anomalies using an assumed charge- and spin-response spectrum. Its phenomenological success would not identify a unique microscopic origin. The original article has an erratum; this review records the correction's identity but has not independently read its contents, and therefore does not reproduce a supposedly corrected derivation. Quantum critical, incoherent-metal and phonon-based explanations require separate discriminating evidence rather than a choice made from one resistivity exponent.","evidenceType":"hypothesis","sourceIds":["source-5880a61b06ec84e6","source-2cdc898b9c5e504c","source-374c8bc13ced83e8"],"conditions":"Fit window, residual subtraction, lifetime convention, angular superconducting exclusions and source version remain explicit.","verificationScope":"Selected primary texts and figures plus independent synthetic identifiability checks; full scientific acceptance remains open."},{"id":"scwiki-h1-claim-limits-and-disputes-2","sectionId":"limits-and-disputes","statement":"Complete scientific acceptance remains open. Selected final passages and figures have been checked, but full version comparisons and raw-data fits remain incomplete. A slope correlation with superconductivity does not establish causation, and a channel contributing to the condensate does not identify the interaction binding its electrons. Retain alternative explanations and distinguish an experimental observable from quantities inferred through a model.","evidenceType":"hypothesis","sourceIds":["source-1610fd228e679225","source-05b2d5ff6757b5eb"],"conditions":"Fit window, residual subtraction, lifetime convention, angular superconducting exclusions and source version remain explicit.","verificationScope":"Selected primary texts and figures plus independent synthetic identifiability checks; full scientific acceptance remains open."},{"id":"scwiki-h1-claim-discovery-implications-1","sectionId":"discovery-implications","statement":"Compare transport, spectroscopy and superconducting response on well-characterized samples, with field, geometry and temperature windows recorded. Use independent changes in disorder, pressure or filling to test whether a proposed scattering process also controls pairing. A useful discovery claim predicts an observable change and survives alternative fits; simply finding another straight resistivity curve adds a candidate observation, not a complete microscopic explanation.","evidenceType":"hypothesis","sourceIds":["source-c1ae7869b672a8e8","source-8135909144b6b16b","source-05b2d5ff6757b5eb"],"conditions":"Fit window, residual subtraction, lifetime convention, angular superconducting exclusions and source version remain explicit.","verificationScope":"Selected primary texts and figures plus independent synthetic identifiability checks; full scientific acceptance remains open."}],"corrections":[{"id":"scwiki-h1-correction-1","description":"Preserve angular superconducting exclusions in high-field ADMR, separate isotropic inelastic scattering from total scattering, and distinguish author-version linewidth fits from final publication evidence.","sourceId":"source-374c8bc13ced83e8","scope":"Experiment and model interpretation."}],"equationChecks":[{"targetSectionId":"mathematical-assumptions","tex":"n_{\\mathrm{eff}}=2BT^2/(BT^2-\\epsilon)","check":"108 residual-subtraction finite-difference checks passed; two quadratic fitting windows and nine mixed-exponent cases also checked. Synthetic data only."}],"materialCases":[{"id":"scwiki-h1-material-1","formula":"La1.35Nd0.4Sr0.25CuO4","sample":"Grissonnanche Nd-LSCO, hole concentration p=0.24 ± 0.005; nominal Sr x=0.25","recordType":"experiment","reportedTemperatureK":11,"tcK":11,"temperatureKind":"transition","temperatureNote":"Zero-resistance transition reported in methods; not the 6 K high-field measurement temperature. Formula follows nominal Sr x=0.25; measured hole concentration p=0.24 ± 0.005 is distinct.","criterion":"zero-resistance","pressureRegime":"ambient","pressureGPa":null,"equilibrium":"unknown","probe":"Electrical resistivity","sourceId":"source-374c8bc13ced83e8","aliases":["Nd-LSCO"]},{"id":"scwiki-h1-material-2","formula":"La1.35Nd0.4Sr0.25CuO4","sample":"Grissonnanche Nd-LSCO, 45 T angular magnetoresistance at p=0.24","recordType":"experiment","reportedTemperatureK":6,"tcK":null,"temperatureKind":"measurement","temperatureNote":"6 K measurement; superconducting angular sectors excluded. Absolute temperature uncertainty about ±1 K, distinct from ±1 mK stability.","criterion":"ADMR-measurement","pressureRegime":"ambient","pressureGPa":null,"equilibrium":"unknown","probe":"Angle-dependent c-axis magnetoresistance","sourceId":"source-374c8bc13ced83e8","aliases":["Nd-LSCO"]}],"sourceMap":[{"startLine":1,"endLine":137,"targetSections":["scope","mathematical-assumptions","experimental-criteria","limits-and-disputes","discovery-implications","related-topics"],"decision":"edited-with-scoped-evidence","note":"Pinned source retained; normal-state criteria, version limits and independently checked fitting ambiguity added."}],"body":"## Scope\n\nA strange metal is identified through unusual normal-state behavior, often including resistivity approximately proportional to temperature after superconductivity is suppressed. It is an observational category, not a uniquely established microscopic phase or order parameter. The early Bi-based transport work and later overdoped-cuprate experiments concern particular specimens and temperature ranges. Their results do not provide a universal slope for all superconductors. Ordinary high-temperature electron–phonon transport can also be linear, so a room-temperature straight line alone is insufficient. [R1](#ref-source-a5d6480d08ee8555) [R2](#ref-source-1610fd228e679225) [R4](#ref-source-374c8bc13ced83e8)\n\nThis article focuses on how observations constrain explanations. Linear resistivity, a transport relaxation rate near a thermal quantum scale, proximity to a quantum critical point and a high superconducting transition temperature are separate propositions. Each requires additional evidence. Even the identity of a relevant lifetime matters: a single-particle linewidth and a current-relaxation rate need not weight scattering processes in the same way. [R3](#ref-source-c1ae7869b672a8e8) [R4](#ref-source-374c8bc13ced83e8) [R6](#ref-source-05b2d5ff6757b5eb)\n\n## Mathematical assumptions\n\nFor a fitted normal-state curve, write $\\rho(T)=\\rho_0+AT+BT^2$. This is an empirical decomposition over a stated interval; its terms do not automatically identify independent microscopic mechanisms. Define a local exponent relative to a trial residual $\\rho_r$ by $n_{\\mathrm{eff}}=d\\ln(\\rho-\\rho_r)/d\\ln T$, wherever the logarithm is defined. Derivatives amplify noise and depend on the residual subtraction. An exponent should therefore accompany its temperature window, uncertainty and treatment of the superconducting region. [R2](#ref-source-1610fd228e679225) [R3](#ref-source-c1ae7869b672a8e8)\n\nAn independent illustration uses exactly quadratic data, $\\rho=\\rho_0+BT^2$. If the trial residual differs by $\\epsilon=\\rho_r-\\rho_0$, then $n_{\\mathrm{eff}}=2BT^2/(BT^2-\\epsilon)$. One hundred and eight finite-difference checks verify this relation. With the correct residual, a positive mixture of linear and quadratic terms gives $n_{\\mathrm{eff}}=(A+2BT)/(A+BT)$, continuously between one and two; nine parameter cases confirm that limit. No abrupt phase boundary is required by this smooth crossover. These are synthetic checks, not fits to a paper's measurements. [R2](#ref-source-1610fd228e679225)\n\nTwo additional synthetic fits use $\\rho=10+0.1T^2$ in arbitrary consistent units. A best straight line over $9\\leq T\\leq11$ has maximum deviation below 0.4% of the mean resistivity; extending the interval to $1\\leq T\\leq20$ raises it above 20%. Thus apparent linearity over a narrow interval can hide curvature. These percentages depend on the chosen example and are not universal acceptance thresholds. Real analysis needs residual plots, independent temperature calibration and a measurement-specific noise model. [R2](#ref-source-1610fd228e679225)\n\nFor parallel conducting channels, conductivities add: $\\sigma_{\\mathrm{dc}}=\\sigma_0+S/\\Gamma$ in a specified Drude convention. If $S$ and $\\sigma_0$ are constant and $\\Gamma\\propto T$, the resulting resistivity is $\\rho=1/(a+b/T)$, which is generally nonlinear. Adding channel resistivities would describe a different circuit. Temperature-dependent spectral weight and finite frequency coverage must also be tested before assigning a lifetime from the total d.c. curve. [R6](#ref-source-05b2d5ff6757b5eb)\n\n## Experimental criteria\n\nGrissonnanche and colleagues measured angle-dependent magnetoresistance in Nd-LSCO at hole concentration $p=0.24\\pm0.005$. The sample's zero-resistance transition is 11 K; the transport measurements use 45 T at 6, 12, 20 and 25 K. At the two lower temperatures, some field orientations still enter a superconducting region. A high field alone therefore does not certify that every angular data point is normal-state transport. [R4](#ref-source-374c8bc13ced83e8)\n\nTheir fit separates a temperature-independent anisotropic contribution from an isotropic temperature-dependent rate, giving $\\alpha=1.2\\pm0.4$ in $\\hbar/\\tau_{\\mathrm{inel}}=\\alpha k_BT$. Total scattering is not isotropic. The analysis uses a bandwidth scale $160\\pm30$ meV constrained by specific heat and omits a low-temperature correction that could change it by about 20% at 6 K. Temperature stability of ±1 mK differs from absolute uncertainty of approximately ±1 K at 6 and 12 K. These qualifications belong with the extracted coefficient. [R4](#ref-source-374c8bc13ced83e8)\n\nRomero and colleagues resolve a narrower Drude channel and a broad background in two FeTe1−xSex films. The final abstract associates most condensate spectral weight with the narrower channel. In the checked author version, the scattering-rate fits use 20–40 K, and linewidths below the approximately 0.2 THz measurement limit cannot be resolved directly. Its frequency variable uses cycles per second, so $h$ appears in $\\Gamma=\\Gamma_0+\\alpha k_BT/h$; an angular-frequency rate instead uses $\\hbar$. A fitted spectral decomposition is stronger evidence than assigning a lifetime from total resistance alone, but it does not uniquely determine the pairing interaction. [R6](#ref-source-05b2d5ff6757b5eb)\n\nCooper and colleagues report that a low-temperature linear contribution extends over a range of LSCO dopings and tracks superconductivity. The checked abstract supports that association, not a reanalysis of its numerical curves. Magic-angle graphene measurements provide another material setting with nearly linear transport; a similar temperature exponent across systems does not prove identical scattering or pairing mechanisms. Material geometry, filling and fit assumptions must accompany cross-system comparisons. [R2](#ref-source-1610fd228e679225) [R5](#ref-source-8135909144b6b16b)\n\n## Limits and disputes\n\nThe marginal-Fermi-liquid proposal organizes anomalies using an assumed charge- and spin-response spectrum. Its phenomenological success would not identify a unique microscopic origin. The original article has an erratum; this review records the correction's identity but has not independently read its contents, and therefore does not reproduce a supposedly corrected derivation. Quantum critical, incoherent-metal and phonon-based explanations require separate discriminating evidence rather than a choice made from one resistivity exponent. [R7](#ref-source-5880a61b06ec84e6) [R8](#ref-source-2cdc898b9c5e504c) [R4](#ref-source-374c8bc13ced83e8)\n\nComplete scientific acceptance remains open. Selected final passages and figures have been checked, but full version comparisons and raw-data fits remain incomplete. A slope correlation with superconductivity does not establish causation, and a channel contributing to the condensate does not identify the interaction binding its electrons. Retain alternative explanations and distinguish an experimental observable from quantities inferred through a model. [R2](#ref-source-1610fd228e679225) [R6](#ref-source-05b2d5ff6757b5eb)\n\n## Discovery implications\n\nCompare transport, spectroscopy and superconducting response on well-characterized samples, with field, geometry and temperature windows recorded. Use independent changes in disorder, pressure or filling to test whether a proposed scattering process also controls pairing. A useful discovery claim predicts an observable change and survives alternative fits; simply finding another straight resistivity curve adds a candidate observation, not a complete microscopic explanation. [R3](#ref-source-c1ae7869b672a8e8) [R5](#ref-source-8135909144b6b16b) [R6](#ref-source-05b2d5ff6757b5eb)\n\n## Related topics\n\n[Linear-T resistivity](/scwiki/linear-t-resistivity), [Planckian dissipation](/scwiki/planckian-dissipation), and [Spin-fluctuation pairing](/scwiki/spin-fluctuation-pairing).","revision":"fdf02bc0add09640378c","sections":[{"id":"scope","title":"Scope","markdown":"## Scope\n\nA strange metal is identified through unusual normal-state behavior, often including resistivity approximately proportional to temperature after superconductivity is suppressed. It is an observational category, not a uniquely established microscopic phase or order parameter. The early Bi-based transport work and later overdoped-cuprate experiments concern particular specimens and temperature ranges. Their results do not provide a universal slope for all superconductors. Ordinary high-temperature electron–phonon transport can also be linear, so a room-temperature straight line alone is insufficient. [R1](#ref-source-a5d6480d08ee8555) [R2](#ref-source-1610fd228e679225) [R4](#ref-source-374c8bc13ced83e8)\n\nThis article focuses on how observations constrain explanations. Linear resistivity, a transport relaxation rate near a thermal quantum scale, proximity to a quantum critical point and a high superconducting transition temperature are separate propositions. Each requires additional evidence. Even the identity of a relevant lifetime matters: a single-particle linewidth and a current-relaxation rate need not weight scattering processes in the same way. [R3](#ref-source-c1ae7869b672a8e8) [R4](#ref-source-374c8bc13ced83e8) [R6](#ref-source-05b2d5ff6757b5eb)"},{"id":"mathematical-assumptions","title":"Mathematical assumptions","markdown":"## Mathematical assumptions\n\nFor a fitted normal-state curve, write $\\rho(T)=\\rho_0+AT+BT^2$. This is an empirical decomposition over a stated interval; its terms do not automatically identify independent microscopic mechanisms. Define a local exponent relative to a trial residual $\\rho_r$ by $n_{\\mathrm{eff}}=d\\ln(\\rho-\\rho_r)/d\\ln T$, wherever the logarithm is defined. Derivatives amplify noise and depend on the residual subtraction. An exponent should therefore accompany its temperature window, uncertainty and treatment of the superconducting region. [R2](#ref-source-1610fd228e679225) [R3](#ref-source-c1ae7869b672a8e8)\n\nAn independent illustration uses exactly quadratic data, $\\rho=\\rho_0+BT^2$. If the trial residual differs by $\\epsilon=\\rho_r-\\rho_0$, then $n_{\\mathrm{eff}}=2BT^2/(BT^2-\\epsilon)$. One hundred and eight finite-difference checks verify this relation. With the correct residual, a positive mixture of linear and quadratic terms gives $n_{\\mathrm{eff}}=(A+2BT)/(A+BT)$, continuously between one and two; nine parameter cases confirm that limit. No abrupt phase boundary is required by this smooth crossover. These are synthetic checks, not fits to a paper's measurements. [R2](#ref-source-1610fd228e679225)\n\nTwo additional synthetic fits use $\\rho=10+0.1T^2$ in arbitrary consistent units. A best straight line over $9\\leq T\\leq11$ has maximum deviation below 0.4% of the mean resistivity; extending the interval to $1\\leq T\\leq20$ raises it above 20%. Thus apparent linearity over a narrow interval can hide curvature. These percentages depend on the chosen example and are not universal acceptance thresholds. Real analysis needs residual plots, independent temperature calibration and a measurement-specific noise model. [R2](#ref-source-1610fd228e679225)\n\nFor parallel conducting channels, conductivities add: $\\sigma_{\\mathrm{dc}}=\\sigma_0+S/\\Gamma$ in a specified Drude convention. If $S$ and $\\sigma_0$ are constant and $\\Gamma\\propto T$, the resulting resistivity is $\\rho=1/(a+b/T)$, which is generally nonlinear. Adding channel resistivities would describe a different circuit. Temperature-dependent spectral weight and finite frequency coverage must also be tested before assigning a lifetime from the total d.c. curve. [R6](#ref-source-05b2d5ff6757b5eb)"},{"id":"experimental-criteria","title":"Experimental criteria","markdown":"## Experimental criteria\n\nGrissonnanche and colleagues measured angle-dependent magnetoresistance in Nd-LSCO at hole concentration $p=0.24\\pm0.005$. The sample's zero-resistance transition is 11 K; the transport measurements use 45 T at 6, 12, 20 and 25 K. At the two lower temperatures, some field orientations still enter a superconducting region. A high field alone therefore does not certify that every angular data point is normal-state transport. [R4](#ref-source-374c8bc13ced83e8)\n\nTheir fit separates a temperature-independent anisotropic contribution from an isotropic temperature-dependent rate, giving $\\alpha=1.2\\pm0.4$ in $\\hbar/\\tau_{\\mathrm{inel}}=\\alpha k_BT$. Total scattering is not isotropic. The analysis uses a bandwidth scale $160\\pm30$ meV constrained by specific heat and omits a low-temperature correction that could change it by about 20% at 6 K. Temperature stability of ±1 mK differs from absolute uncertainty of approximately ±1 K at 6 and 12 K. These qualifications belong with the extracted coefficient. [R4](#ref-source-374c8bc13ced83e8)\n\nRomero and colleagues resolve a narrower Drude channel and a broad background in two FeTe1−xSex films. The final abstract associates most condensate spectral weight with the narrower channel. In the checked author version, the scattering-rate fits use 20–40 K, and linewidths below the approximately 0.2 THz measurement limit cannot be resolved directly. Its frequency variable uses cycles per second, so $h$ appears in $\\Gamma=\\Gamma_0+\\alpha k_BT/h$; an angular-frequency rate instead uses $\\hbar$. A fitted spectral decomposition is stronger evidence than assigning a lifetime from total resistance alone, but it does not uniquely determine the pairing interaction. [R6](#ref-source-05b2d5ff6757b5eb)\n\nCooper and colleagues report that a low-temperature linear contribution extends over a range of LSCO dopings and tracks superconductivity. The checked abstract supports that association, not a reanalysis of its numerical curves. Magic-angle graphene measurements provide another material setting with nearly linear transport; a similar temperature exponent across systems does not prove identical scattering or pairing mechanisms. Material geometry, filling and fit assumptions must accompany cross-system comparisons. [R2](#ref-source-1610fd228e679225) [R5](#ref-source-8135909144b6b16b)"},{"id":"limits-and-disputes","title":"Limits and disputes","markdown":"## Limits and disputes\n\nThe marginal-Fermi-liquid proposal organizes anomalies using an assumed charge- and spin-response spectrum. Its phenomenological success would not identify a unique microscopic origin. The original article has an erratum; this review records the correction's identity but has not independently read its contents, and therefore does not reproduce a supposedly corrected derivation. Quantum critical, incoherent-metal and phonon-based explanations require separate discriminating evidence rather than a choice made from one resistivity exponent. [R7](#ref-source-5880a61b06ec84e6) [R8](#ref-source-2cdc898b9c5e504c) [R4](#ref-source-374c8bc13ced83e8)\n\nComplete scientific acceptance remains open. Selected final passages and figures have been checked, but full version comparisons and raw-data fits remain incomplete. A slope correlation with superconductivity does not establish causation, and a channel contributing to the condensate does not identify the interaction binding its electrons. Retain alternative explanations and distinguish an experimental observable from quantities inferred through a model. [R2](#ref-source-1610fd228e679225) [R6](#ref-source-05b2d5ff6757b5eb)"},{"id":"discovery-implications","title":"Discovery implications","markdown":"## Discovery implications\n\nCompare transport, spectroscopy and superconducting response on well-characterized samples, with field, geometry and temperature windows recorded. Use independent changes in disorder, pressure or filling to test whether a proposed scattering process also controls pairing. A useful discovery claim predicts an observable change and survives alternative fits; simply finding another straight resistivity curve adds a candidate observation, not a complete microscopic explanation. [R3](#ref-source-c1ae7869b672a8e8) [R5](#ref-source-8135909144b6b16b) [R6](#ref-source-05b2d5ff6757b5eb)"},{"id":"related-topics","title":"Related topics","markdown":"## Related topics\n\n[Linear-T resistivity](/scwiki/linear-t-resistivity), [Planckian dissipation](/scwiki/planckian-dissipation), and [Spin-fluctuation pairing](/scwiki/spin-fluctuation-pairing)."},{"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| La1.35Nd0.4Sr0.25CuO4 (aliases: Nd-LSCO); Grissonnanche Nd-LSCO, hole concentration p=0.24 ± 0.005; nominal Sr x=0.25 | 11 K; Zero-resistance transition reported in methods; not the 6 K high-field measurement temperature. Formula follows nominal Sr x=0.25; measured hole concentration p=0.24 ± 0.005 is distinct. | transition; zero-resistance | Electrical resistivity | ambient; unknown GPa | unknown | experiment; [source](#ref-source-374c8bc13ced83e8) |\n| La1.35Nd0.4Sr0.25CuO4 (aliases: Nd-LSCO); Grissonnanche Nd-LSCO, 45 T angular magnetoresistance at p=0.24 | 6 K; 6 K measurement; superconducting angular sectors excluded. Absolute temperature uncertainty about ±1 K, distinct from ±1 mK stability. | measurement; ADMR-measurement | Angle-dependent c-axis magnetoresistance | ambient; unknown GPa | unknown | experiment; [source](#ref-source-374c8bc13ced83e8) |"}],"markdown":"# Strange metals and linear-temperature resistivity\n\nEvaluate normal-state transport without conflating a fitted exponent, a relaxation time, quantum criticality and the superconducting mechanism.\n\n## Scope\n\nA strange metal is identified through unusual normal-state behavior, often including resistivity approximately proportional to temperature after superconductivity is suppressed. It is an observational category, not a uniquely established microscopic phase or order parameter. The early Bi-based transport work and later overdoped-cuprate experiments concern particular specimens and temperature ranges. Their results do not provide a universal slope for all superconductors. Ordinary high-temperature electron–phonon transport can also be linear, so a room-temperature straight line alone is insufficient. [R1](#ref-source-a5d6480d08ee8555) [R2](#ref-source-1610fd228e679225) [R4](#ref-source-374c8bc13ced83e8)\n\nThis article focuses on how observations constrain explanations. Linear resistivity, a transport relaxation rate near a thermal quantum scale, proximity to a quantum critical point and a high superconducting transition temperature are separate propositions. Each requires additional evidence. Even the identity of a relevant lifetime matters: a single-particle linewidth and a current-relaxation rate need not weight scattering processes in the same way. [R3](#ref-source-c1ae7869b672a8e8) [R4](#ref-source-374c8bc13ced83e8) [R6](#ref-source-05b2d5ff6757b5eb)\n\n## Mathematical assumptions\n\nFor a fitted normal-state curve, write $\\rho(T)=\\rho_0+AT+BT^2$. This is an empirical decomposition over a stated interval; its terms do not automatically identify independent microscopic mechanisms. Define a local exponent relative to a trial residual $\\rho_r$ by $n_{\\mathrm{eff}}=d\\ln(\\rho-\\rho_r)/d\\ln T$, wherever the logarithm is defined. Derivatives amplify noise and depend on the residual subtraction. An exponent should therefore accompany its temperature window, uncertainty and treatment of the superconducting region. [R2](#ref-source-1610fd228e679225) [R3](#ref-source-c1ae7869b672a8e8)\n\nAn independent illustration uses exactly quadratic data, $\\rho=\\rho_0+BT^2$. If the trial residual differs by $\\epsilon=\\rho_r-\\rho_0$, then $n_{\\mathrm{eff}}=2BT^2/(BT^2-\\epsilon)$. One hundred and eight finite-difference checks verify this relation. With the correct residual, a positive mixture of linear and quadratic terms gives $n_{\\mathrm{eff}}=(A+2BT)/(A+BT)$, continuously between one and two; nine parameter cases confirm that limit. No abrupt phase boundary is required by this smooth crossover. These are synthetic checks, not fits to a paper's measurements. [R2](#ref-source-1610fd228e679225)\n\nTwo additional synthetic fits use $\\rho=10+0.1T^2$ in arbitrary consistent units. A best straight line over $9\\leq T\\leq11$ has maximum deviation below 0.4% of the mean resistivity; extending the interval to $1\\leq T\\leq20$ raises it above 20%. Thus apparent linearity over a narrow interval can hide curvature. These percentages depend on the chosen example and are not universal acceptance thresholds. Real analysis needs residual plots, independent temperature calibration and a measurement-specific noise model. [R2](#ref-source-1610fd228e679225)\n\nFor parallel conducting channels, conductivities add: $\\sigma_{\\mathrm{dc}}=\\sigma_0+S/\\Gamma$ in a specified Drude convention. If $S$ and $\\sigma_0$ are constant and $\\Gamma\\propto T$, the resulting resistivity is $\\rho=1/(a+b/T)$, which is generally nonlinear. Adding channel resistivities would describe a different circuit. Temperature-dependent spectral weight and finite frequency coverage must also be tested before assigning a lifetime from the total d.c. curve. [R6](#ref-source-05b2d5ff6757b5eb)\n\n## Experimental criteria\n\nGrissonnanche and colleagues measured angle-dependent magnetoresistance in Nd-LSCO at hole concentration $p=0.24\\pm0.005$. The sample's zero-resistance transition is 11 K; the transport measurements use 45 T at 6, 12, 20 and 25 K. At the two lower temperatures, some field orientations still enter a superconducting region. A high field alone therefore does not certify that every angular data point is normal-state transport. [R4](#ref-source-374c8bc13ced83e8)\n\nTheir fit separates a temperature-independent anisotropic contribution from an isotropic temperature-dependent rate, giving $\\alpha=1.2\\pm0.4$ in $\\hbar/\\tau_{\\mathrm{inel}}=\\alpha k_BT$. Total scattering is not isotropic. The analysis uses a bandwidth scale $160\\pm30$ meV constrained by specific heat and omits a low-temperature correction that could change it by about 20% at 6 K. Temperature stability of ±1 mK differs from absolute uncertainty of approximately ±1 K at 6 and 12 K. These qualifications belong with the extracted coefficient. [R4](#ref-source-374c8bc13ced83e8)\n\nRomero and colleagues resolve a narrower Drude channel and a broad background in two FeTe1−xSex films. The final abstract associates most condensate spectral weight with the narrower channel. In the checked author version, the scattering-rate fits use 20–40 K, and linewidths below the approximately 0.2 THz measurement limit cannot be resolved directly. Its frequency variable uses cycles per second, so $h$ appears in $\\Gamma=\\Gamma_0+\\alpha k_BT/h$; an angular-frequency rate instead uses $\\hbar$. A fitted spectral decomposition is stronger evidence than assigning a lifetime from total resistance alone, but it does not uniquely determine the pairing interaction. [R6](#ref-source-05b2d5ff6757b5eb)\n\nCooper and colleagues report that a low-temperature linear contribution extends over a range of LSCO dopings and tracks superconductivity. The checked abstract supports that association, not a reanalysis of its numerical curves. Magic-angle graphene measurements provide another material setting with nearly linear transport; a similar temperature exponent across systems does not prove identical scattering or pairing mechanisms. Material geometry, filling and fit assumptions must accompany cross-system comparisons. [R2](#ref-source-1610fd228e679225) [R5](#ref-source-8135909144b6b16b)\n\n## Limits and disputes\n\nThe marginal-Fermi-liquid proposal organizes anomalies using an assumed charge- and spin-response spectrum. Its phenomenological success would not identify a unique microscopic origin. The original article has an erratum; this review records the correction's identity but has not independently read its contents, and therefore does not reproduce a supposedly corrected derivation. Quantum critical, incoherent-metal and phonon-based explanations require separate discriminating evidence rather than a choice made from one resistivity exponent. [R7](#ref-source-5880a61b06ec84e6) [R8](#ref-source-2cdc898b9c5e504c) [R4](#ref-source-374c8bc13ced83e8)\n\nComplete scientific acceptance remains open. Selected final passages and figures have been checked, but full version comparisons and raw-data fits remain incomplete. A slope correlation with superconductivity does not establish causation, and a channel contributing to the condensate does not identify the interaction binding its electrons. Retain alternative explanations and distinguish an experimental observable from quantities inferred through a model. [R2](#ref-source-1610fd228e679225) [R6](#ref-source-05b2d5ff6757b5eb)\n\n## Discovery implications\n\nCompare transport, spectroscopy and superconducting response on well-characterized samples, with field, geometry and temperature windows recorded. Use independent changes in disorder, pressure or filling to test whether a proposed scattering process also controls pairing. A useful discovery claim predicts an observable change and survives alternative fits; simply finding another straight resistivity curve adds a candidate observation, not a complete microscopic explanation. [R3](#ref-source-c1ae7869b672a8e8) [R5](#ref-source-8135909144b6b16b) [R6](#ref-source-05b2d5ff6757b5eb)\n\n## Related topics\n\n[Linear-T resistivity](/scwiki/linear-t-resistivity), [Planckian dissipation](/scwiki/planckian-dissipation), and [Spin-fluctuation pairing](/scwiki/spin-fluctuation-pairing).\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| La1.35Nd0.4Sr0.25CuO4 (aliases: Nd-LSCO); Grissonnanche Nd-LSCO, hole concentration p=0.24 ± 0.005; nominal Sr x=0.25 | 11 K; Zero-resistance transition reported in methods; not the 6 K high-field measurement temperature. Formula follows nominal Sr x=0.25; measured hole concentration p=0.24 ± 0.005 is distinct. | transition; zero-resistance | Electrical resistivity | ambient; unknown GPa | unknown | experiment; [source](#ref-source-374c8bc13ced83e8) |\n| La1.35Nd0.4Sr0.25CuO4 (aliases: Nd-LSCO); Grissonnanche Nd-LSCO, 45 T angular magnetoresistance at p=0.24 | 6 K; 6 K measurement; superconducting angular sectors excluded. Absolute temperature uncertainty about ±1 K, distinct from ±1 mK stability. | measurement; ADMR-measurement | Angle-dependent c-axis magnetoresistance | ambient; unknown GPa | unknown | experiment; [source](#ref-source-374c8bc13ced83e8) |\n\n## Sources\n\n### Ref source-a5d6480d08ee8555\n\n[R1] Normal-state transport properties of Bi2+xSr2-yCuO6+delta crystals (1990). [DOI 10.1103/PhysRevB.41.846](https://doi.org/10.1103/PhysRevB.41.846). Publication: journal-article. Check: primary-abstract-scoped-check. Checked: 2026-10-18. Publisher abstract only: anisotropic normal-state transport in Bi-based crystals. Full measurement protocol and numerical curves not checked.\n### Ref source-1610fd228e679225\n\n[R2] Anomalous Criticality in the Electrical Resistivity of La2-xSrxCuO4 (2009). [DOI 10.1126/science.1165015](https://doi.org/10.1126/science.1165015). Publication: journal-article. Check: primary-abstract-and-publication-check. Checked: 2026-10-19. Primary abstract reproduced by PubMed checked. Online 11 December 2008; issue 30 January 2009. Publisher full text was unavailable; numerical curves and measurement protocols remain unaudited here.\n### Ref source-c1ae7869b672a8e8\n\n[R3] Universal T-linear resistivity and Planckian dissipation in overdoped cuprates (2019). [DOI 10.1038/s41567-018-0334-2](https://doi.org/10.1038/s41567-018-0334-2). Publication: journal-article. Check: earlier-author-manuscript-scoped-check. Checked: 2026-10-18. Selected v1 pp. 4, 7–8 and Figs. 1–2 captions: Drude assumptions, film method and magnetoresistance correction. Published volume year 2019; final-version comparison and complete data fitting remain open.\n### Ref source-374c8bc13ced83e8\n\n[R4] Linear-in temperature resistivity from an isotropic Planckian scattering rate (2021). [DOI 10.1038/s41586-021-03697-8](https://doi.org/10.1038/s41586-021-03697-8). Publication: journal-article. Check: selected-final-methods-results-and-figure-check. Checked: 2026-10-19. Final results and selected methods read; printed page 669, Figure 2 visually checked. Compared selected author v2 passages. Temperature stability, absolute error, angular superconducting regions and fitted bandwidth distinguished. Complete fitting and raw-data reproduction remain open.\n### Ref source-8135909144b6b16b\n\n[R5] Strange Metal in Magic-Angle Graphene with near Planckian Dissipation (2020). [DOI 10.1103/PhysRevLett.124.076801](https://doi.org/10.1103/PhysRevLett.124.076801). Publication: journal-article. Check: primary-fulltext-scoped-check. Checked: 2026-10-18. Selected published pp. 1–4, Fig. 1 and Eq. (1). Four-probe device, filling dependence and low-temperature SdH parameter assumptions checked; supplementary fits not reproduced.\n### Ref source-05b2d5ff6757b5eb\n\n[R6] Planckian scattering and parallel conduction channels in an iron chalcogenide superconductor (2026). [DOI 10.1038/s41567-026-03266-8](https://doi.org/10.1038/s41567-026-03266-8). Publication: journal-article. Check: selected-author-figure-and-final-abstract-check. Checked: 2026-10-19. Author v1, 1 May 2025: selected methods and results, pages 1–4, read; page 4 Figure 3 visually checked. Final publisher abstract and publication date, 23 April 2026, checked. Final full text requires access; the attempted PDF returned HTML. Complete version comparison and spectral-weight calibration remain open.\n### Ref source-5880a61b06ec84e6\n\n[R7] Phenomenology of the normal state of Cu-O high-temperature superconductors (1989). [DOI 10.1103/PhysRevLett.63.1996](https://doi.org/10.1103/PhysRevLett.63.1996). Publication: journal-article. Check: publisher-abstract-check. Checked: 2026-10-19. Published 30 October 1989. Marginal-Fermi-liquid hypothesis checked at abstract level. The linked 1990 erratum is recorded separately; complete corrected derivation remains open.\n### Ref source-2cdc898b9c5e504c\n\n[R8] Erratum: Phenomenology of the normal state of Cu-O high-temperature superconductors (1990). [DOI 10.1103/PhysRevLett.64.497](https://doi.org/10.1103/PhysRevLett.64.497). Publication: journal-article. Check: publisher-erratum-identity-check. Checked: 2026-10-19. Published 22 January 1990. Publisher linkage and identity verified. PDF endpoint returned 403; correction contents have not been independently read, so no corrected formula is attributed to it.\n\n## Claim evidence and conditions\n\n### scwiki-h1-claim-scope-1\n\nA strange metal is identified through unusual normal-state behavior, often including resistivity approximately proportional to temperature after superconductivity is suppressed. It is an observational category, not a uniquely established microscopic phase or order parameter. The early Bi-based transport work and later overdoped-cuprate experiments concern particular specimens and temperature ranges. Their results do not provide a universal slope for all superconductors. Ordinary high-temperature electron–phonon transport can also be linear, so a room-temperature straight line alone is insufficient.\n\nEvidence: hypothesis. Sources: source-a5d6480d08ee8555, source-1610fd228e679225, source-374c8bc13ced83e8.\n\nConditions: Fit window, residual subtraction, lifetime convention, angular superconducting exclusions and source version remain explicit.\n\nVerification scope: Selected primary texts and figures plus independent synthetic identifiability checks; full scientific acceptance remains open.\n\n### scwiki-h1-claim-scope-2\n\nThis article focuses on how observations constrain explanations. Linear resistivity, a transport relaxation rate near a thermal quantum scale, proximity to a quantum critical point and a high superconducting transition temperature are separate propositions. Each requires additional evidence. Even the identity of a relevant lifetime matters: a single-particle linewidth and a current-relaxation rate need not weight scattering processes in the same way.\n\nEvidence: hypothesis. Sources: source-c1ae7869b672a8e8, source-374c8bc13ced83e8, source-05b2d5ff6757b5eb.\n\nConditions: Fit window, residual subtraction, lifetime convention, angular superconducting exclusions and source version remain explicit.\n\nVerification scope: Selected primary texts and figures plus independent synthetic identifiability checks; full scientific acceptance remains open.\n\n### scwiki-h1-claim-mathematical-assumptions-1\n\nFor a fitted normal-state curve, write $\\rho(T)=\\rho_0+AT+BT^2$. This is an empirical decomposition over a stated interval; its terms do not automatically identify independent microscopic mechanisms. Define a local exponent relative to a trial residual $\\rho_r$ by $n_{\\mathrm{eff}}=d\\ln(\\rho-\\rho_r)/d\\ln T$, wherever the logarithm is defined. Derivatives amplify noise and depend on the residual subtraction. An exponent should therefore accompany its temperature window, uncertainty and treatment of the superconducting region.\n\nEvidence: theory. Sources: source-1610fd228e679225, source-c1ae7869b672a8e8.\n\nConditions: Fit window, residual subtraction, lifetime convention, angular superconducting exclusions and source version remain explicit.\n\nVerification scope: Selected primary texts and figures plus independent synthetic identifiability checks; full scientific acceptance remains open.\n\n### scwiki-h1-claim-mathematical-assumptions-2\n\nAn independent illustration uses exactly quadratic data, $\\rho=\\rho_0+BT^2$. If the trial residual differs by $\\epsilon=\\rho_r-\\rho_0$, then $n_{\\mathrm{eff}}=2BT^2/(BT^2-\\epsilon)$. One hundred and eight finite-difference checks verify this relation. With the correct residual, a positive mixture of linear and quadratic terms gives $n_{\\mathrm{eff}}=(A+2BT)/(A+BT)$, continuously between one and two; nine parameter cases confirm that limit. No abrupt phase boundary is required by this smooth crossover. These are synthetic checks, not fits to a paper's measurements.\n\nEvidence: theory. Sources: source-1610fd228e679225.\n\nConditions: Fit window, residual subtraction, lifetime convention, angular superconducting exclusions and source version remain explicit.\n\nVerification scope: Selected primary texts and figures plus independent synthetic identifiability checks; full scientific acceptance remains open.\n\n### scwiki-h1-claim-mathematical-assumptions-3\n\nTwo additional synthetic fits use $\\rho=10+0.1T^2$ in arbitrary consistent units. A best straight line over $9\\leq T\\leq11$ has maximum deviation below 0.4% of the mean resistivity; extending the interval to $1\\leq T\\leq20$ raises it above 20%. Thus apparent linearity over a narrow interval can hide curvature. These percentages depend on the chosen example and are not universal acceptance thresholds. Real analysis needs residual plots, independent temperature calibration and a measurement-specific noise model.\n\nEvidence: theory. Sources: source-1610fd228e679225.\n\nConditions: Fit window, residual subtraction, lifetime convention, angular superconducting exclusions and source version remain explicit.\n\nVerification scope: Selected primary texts and figures plus independent synthetic identifiability checks; full scientific acceptance remains open.\n\n### scwiki-h1-claim-mathematical-assumptions-4\n\nFor parallel conducting channels, conductivities add: $\\sigma_{\\mathrm{dc}}=\\sigma_0+S/\\Gamma$ in a specified Drude convention. If $S$ and $\\sigma_0$ are constant and $\\Gamma\\propto T$, the resulting resistivity is $\\rho=1/(a+b/T)$, which is generally nonlinear. Adding channel resistivities would describe a different circuit. Temperature-dependent spectral weight and finite frequency coverage must also be tested before assigning a lifetime from the total d.c. curve.\n\nEvidence: theory. Sources: source-05b2d5ff6757b5eb.\n\nConditions: Fit window, residual subtraction, lifetime convention, angular superconducting exclusions and source version remain explicit.\n\nVerification scope: Selected primary texts and figures plus independent synthetic identifiability checks; full scientific acceptance remains open.\n\n### scwiki-h1-claim-experimental-criteria-1\n\nGrissonnanche and colleagues measured angle-dependent magnetoresistance in Nd-LSCO at hole concentration $p=0.24\\pm0.005$. The sample's zero-resistance transition is 11 K; the transport measurements use 45 T at 6, 12, 20 and 25 K. At the two lower temperatures, some field orientations still enter a superconducting region. A high field alone therefore does not certify that every angular data point is normal-state transport.\n\nEvidence: experiment. Sources: source-374c8bc13ced83e8.\n\nConditions: Fit window, residual subtraction, lifetime convention, angular superconducting exclusions and source version remain explicit.\n\nVerification scope: Selected primary texts and figures plus independent synthetic identifiability checks; full scientific acceptance remains open.\n\n### scwiki-h1-claim-experimental-criteria-2\n\nTheir fit separates a temperature-independent anisotropic contribution from an isotropic temperature-dependent rate, giving $\\alpha=1.2\\pm0.4$ in $\\hbar/\\tau_{\\mathrm{inel}}=\\alpha k_BT$. Total scattering is not isotropic. The analysis uses a bandwidth scale $160\\pm30$ meV constrained by specific heat and omits a low-temperature correction that could change it by about 20% at 6 K. Temperature stability of ±1 mK differs from absolute uncertainty of approximately ±1 K at 6 and 12 K. These qualifications belong with the extracted coefficient.\n\nEvidence: experiment. Sources: source-374c8bc13ced83e8.\n\nConditions: Fit window, residual subtraction, lifetime convention, angular superconducting exclusions and source version remain explicit.\n\nVerification scope: Selected primary texts and figures plus independent synthetic identifiability checks; full scientific acceptance remains open.\n\n### scwiki-h1-claim-experimental-criteria-3\n\nRomero and colleagues resolve a narrower Drude channel and a broad background in two FeTe1−xSex films. The final abstract associates most condensate spectral weight with the narrower channel. In the checked author version, the scattering-rate fits use 20–40 K, and linewidths below the approximately 0.2 THz measurement limit cannot be resolved directly. Its frequency variable uses cycles per second, so $h$ appears in $\\Gamma=\\Gamma_0+\\alpha k_BT/h$; an angular-frequency rate instead uses $\\hbar$. A fitted spectral decomposition is stronger evidence than assigning a lifetime from total resistance alone, but it does not uniquely determine the pairing interaction.\n\nEvidence: experiment. Sources: source-05b2d5ff6757b5eb.\n\nConditions: Fit window, residual subtraction, lifetime convention, angular superconducting exclusions and source version remain explicit.\n\nVerification scope: Selected primary texts and figures plus independent synthetic identifiability checks; full scientific acceptance remains open.\n\n### scwiki-h1-claim-experimental-criteria-4\n\nCooper and colleagues report that a low-temperature linear contribution extends over a range of LSCO dopings and tracks superconductivity. The checked abstract supports that association, not a reanalysis of its numerical curves. Magic-angle graphene measurements provide another material setting with nearly linear transport; a similar temperature exponent across systems does not prove identical scattering or pairing mechanisms. Material geometry, filling and fit assumptions must accompany cross-system comparisons.\n\nEvidence: experiment. Sources: source-1610fd228e679225, source-8135909144b6b16b.\n\nConditions: Fit window, residual subtraction, lifetime convention, angular superconducting exclusions and source version remain explicit.\n\nVerification scope: Selected primary texts and figures plus independent synthetic identifiability checks; full scientific acceptance remains open.\n\n### scwiki-h1-claim-limits-and-disputes-1\n\nThe marginal-Fermi-liquid proposal organizes anomalies using an assumed charge- and spin-response spectrum. Its phenomenological success would not identify a unique microscopic origin. The original article has an erratum; this review records the correction's identity but has not independently read its contents, and therefore does not reproduce a supposedly corrected derivation. Quantum critical, incoherent-metal and phonon-based explanations require separate discriminating evidence rather than a choice made from one resistivity exponent.\n\nEvidence: hypothesis. Sources: source-5880a61b06ec84e6, source-2cdc898b9c5e504c, source-374c8bc13ced83e8.\n\nConditions: Fit window, residual subtraction, lifetime convention, angular superconducting exclusions and source version remain explicit.\n\nVerification scope: Selected primary texts and figures plus independent synthetic identifiability checks; full scientific acceptance remains open.\n\n### scwiki-h1-claim-limits-and-disputes-2\n\nComplete scientific acceptance remains open. Selected final passages and figures have been checked, but full version comparisons and raw-data fits remain incomplete. A slope correlation with superconductivity does not establish causation, and a channel contributing to the condensate does not identify the interaction binding its electrons. Retain alternative explanations and distinguish an experimental observable from quantities inferred through a model.\n\nEvidence: hypothesis. Sources: source-1610fd228e679225, source-05b2d5ff6757b5eb.\n\nConditions: Fit window, residual subtraction, lifetime convention, angular superconducting exclusions and source version remain explicit.\n\nVerification scope: Selected primary texts and figures plus independent synthetic identifiability checks; full scientific acceptance remains open.\n\n### scwiki-h1-claim-discovery-implications-1\n\nCompare transport, spectroscopy and superconducting response on well-characterized samples, with field, geometry and temperature windows recorded. Use independent changes in disorder, pressure or filling to test whether a proposed scattering process also controls pairing. A useful discovery claim predicts an observable change and survives alternative fits; simply finding another straight resistivity curve adds a candidate observation, not a complete microscopic explanation.\n\nEvidence: hypothesis. Sources: source-c1ae7869b672a8e8, source-8135909144b6b16b, source-05b2d5ff6757b5eb.\n\nConditions: Fit window, residual subtraction, lifetime convention, angular superconducting exclusions and source version remain explicit.\n\nVerification scope: Selected primary texts and figures plus independent synthetic identifiability checks; full scientific acceptance remains open.\n\n## Revision and review\n\nArticle ID: scwiki-h1. Revision: fdf02bc0add09640378c. Updated: 2026-10-18T16:26:45.370525+00:00.\n\nReview scope: Selected final Nd-LSCO methods and Figure 2, Romero author methods and Figure 3 with final abstract, inherited graphene evidence, primary abstracts and independent synthetic fit checks.\n\n- Complete scientific acceptance remains open.\n- Full raw-data fits, wider competing literature and final-version comparisons remain incomplete.\n- Cooper evidence is abstract-level here; Varma erratum identity is recorded without claiming its contents were checked.\n- Synthetic exponents and fitting windows do not establish a microscopic mechanism or quantum critical point.\n\nSource: [H_anomalous_normal_state/H1_strange_metal_linear_T.md](https://github.com/JackZH26/jzis-superconductivity/blob/0a7c9d6696804ec26aa12f8eed68b55c9b3c0fcf/H_anomalous_normal_state/H1_strange_metal_linear_T.md), commit 0a7c9d6696804ec26aa12f8eed68b55c9b3c0fcf, SHA-256 d5c5f605dcb2d5fe7ea2eb72ba5530c10f3938d54760cba6d33d9656651bfc39.\n","wordCount":942}}