# Strain tuning: calibrated deformation and superconducting criteria

Separate nominal mismatch from measured strain, retain mechanical boundary conditions, and distinguish magnetic midpoints from resistive transitions.

## Scope

Strain is a directional deformation relative to a stated reference structure. A uniaxially loaded crystal, a clamped epitaxial film and a hydrostatically compressed sample follow different mechanical paths. Applied displacement is not necessarily sample strain: mounting adhesive, thermal contraction, bending and fracture can all intervene. The useful control variable is the calibrated deformation in the region probed, together with its uncertainty and history. In the ideal uniaxial-stress geometry, transverse Poisson strains remain nonzero: controlling one loading axis does not set every other strain component to zero. A displacement sensor also does not directly measure the strain throughout a specimen. [R1](#ref-source-363388aa03563c00) [R3](#ref-source-c9a97c501c718b62)

Separate the early Sr2RuO4 experiments. Hicks's 2014 Science study reported different responses for loading along the crystallographic ⟨100⟩ and ⟨110⟩ directions, within an approximately 0.23% accessible range. The later Steppke study reached the much larger compressive strain associated with a transition near 3.4 K. These are distinct measurements, not interchangeable references for one apparatus or peak. The earlier result is checked here only through the authors' institutional abstract. [R2](#ref-source-2c98c9257f2c4d46) [R3](#ref-source-c9a97c501c718b62)

## Mathematical assumptions

For a lattice parameter relative to a relaxed reference, engineering strain is $\epsilon=(a-a_0)/a_0$. Nominal epitaxial mismatch uses $f=(a_{\rm sub}-a_{\rm ref})/a_{\rm ref}$ instead. Neither a substrate name nor this calculation establishes the strain remaining after relaxation. Report reference composition, phase, temperature and orientation; compare actual film lattice parameters with that same reference. [R4](#ref-source-4b5b65a5047eb1a9)

In small-deformation elasticity, $\epsilon_{ij}=(\partial_i u_j+\partial_j u_i)/2$ and $\sigma_{ij}=C_{ijkl}\epsilon_{kl}$. As an explicitly isotropic illustration, a film with equal in-plane strains $\epsilon_{xx}=\epsilon_{yy}=f$ and a traction-free surface has $\epsilon_{zz}=-2\nu f/(1-\nu)$. Positive Poisson ratio therefore permits out-of-plane expansion under in-plane compression. This illustration is not an anisotropic nickelate fit, and it does not convert epitaxial mismatch into an equivalent hydrostatic pressure. [R1](#ref-source-363388aa03563c00) [R4](#ref-source-4b5b65a5047eb1a9)

Hicks's simplified adhesive model gives a load-transfer length $\lambda=\sqrt{Etd/(nG_e)}$, with sample Young's modulus $E$, sample thickness $t$, adhesive thickness $d$, adhesive shear modulus $G_e$, and one or two bonded faces $n$. For symmetric ends, displacement is distributed over approximately $L+2\lambda$, not just the exposed length $L$. With $E=182$ GPa, $t=50$ micrometres, $d=10$ micrometres, $n=2$ and $G_e=6$ GPa, the model gives 87 micrometres, consistent with the paper's approximately 90 micrometres. For an illustrative 1 mm exposed length, dividing displacement by $L$ alone overestimates the model's central strain by about 17% relative to that strain. This is local arithmetic, not a recalibration of Steppke's samples. Rigid plates, much softer adhesive, long bonded regions and uniform strain across the sample cross-section are assumptions. [R1](#ref-source-363388aa03563c00)

The same author manuscript's Appendix A contains a numerical discrepancy worth preserving. Using its printed Eq. A1 and the parameters above, a 0.2% sample strain gives a displacement-over-glue-thickness shear of approximately 1.74% and a shear stress of 105 MPa; the adjacent prose instead reports 1.3% and 80 MPa. The scalar shear here follows that equation's convention, not the half-sized off-diagonal strain-tensor component. This substitution check does not establish a formal correction or a failure threshold. The paper itself notes uncertain low-temperature adhesive properties; room-temperature tensile strength is not a measured cryogenic shear-strength limit. [R1](#ref-source-363388aa03563c00)

## Experimental criteria

Steppke measured magnetic transitions using mutual inductance, with approximately 0.2 Oe excitation at 1–20 kHz, and used a capacitive displacement sensor. Figure 4 defines the plotted transition temperatures at 50% of the magnetic response; the 20% and 80% levels show transition width. The reported peak strain is approximately −0.60% with a ±0.06 percentage-point uncertainty from four samples, while individual strain calibration was estimated to have roughly 20% uncertainty. These are different uncertainty statements. [R3](#ref-source-c9a97c501c718b62)

The often-quoted 3.4 K scale is not a universal sample maximum: sample 5 reached approximately 3.5 K. Resistive transitions in the two contacted specimens did not exceed the highest magnetic transition by more than 0.08 K. That comparison does not redefine a magnetic midpoint as zero resistance. A flat feature near zero strain in sample 1 arose after the sample broke during cooling and needed compression to re-engage; it should not be fitted as an intrinsic phase boundary. Reported recovery of magnetic curves after unloading other checks supports reversible deformation under those conditions, not a guarantee that every mounting survives or that thermodynamic equilibrium has been established. The critical-field measurements on sample 4 use intersections of linear fits around a susceptibility cusp; that separate procedure must not replace the 50% criterion for the Figure 4 temperature-versus-strain data. [R3](#ref-source-c9a97c501c718b62)

Bhatt's final Figure 1 labels nominal/measured mismatch pairs, respectively, as SLAO −2.0%/−1.6%, LAO −1.2%/−0.9%, NGO +0.7%/+0.6% and STO +1.9%/+1.8%. These final labels replace several different measured values in the inherited chapter. The SLAO film has a broad resistive transition, with onset near 42 K and zero near 2 K; those endpoints cannot be merged into a 42 K zero-resistance claim. [R4](#ref-source-4b5b65a5047eb1a9)

Ko's publicly archived author manuscript now supplies selected original methods and criteria. It reports sample A1 with onset at 42.4 K and zero resistance below 2.2 K; the latter is not an exact 2.2 K transition value. Its field-dependent analysis instead uses 90% of the normal-state resistance near onset. The methods describe approximately 100 kHz low-pass filtering; the text warns that observing zero resistance requires adequate radiation filtering. The reported diamagnetic response belongs to sample A12, so it must not be attached to A1 as a same-specimen measurement. The March 2026 correction fixes published resistivity-axis units to mΩ cm and the Figure 3d horizontal label to temperature $T$, not $T_c$. The archived manuscript already has mΩ cm but still labels that axis $T_c$; it is not a verified copy of the corrected journal version. Existing rounded film records retain Bhatt's final passage, while the added A1 onset record cites the author manuscript. No raw-data refit or full final-version comparison is claimed. [R4](#ref-source-4b5b65a5047eb1a9) [R5](#ref-source-98849f3ad0a2df49) [R6](#ref-source-acee7fe0af86cc44)


The comparisons below retain the measured quantity and specimen history; none supplies a universal conversion from applied strain to superconducting temperature.

| Experiment or model | Measured or defined quantity | Interpretation boundary |
|---|---|---|
| Hicks adhesive model [R1](#ref-source-363388aa03563c00) | Displacement shared by exposed crystal and bonded ends | Ideal geometry and uncertain glue modulus; local arithmetic is not a strain map |
| Steppke Figure 4 [R3](#ref-source-c9a97c501c718b62) | Magnetic 50% midpoint; 20–80% transition width | Normalized strain scales; broken sample 1 is identified |
| Steppke sample 4 critical-field scans [R3](#ref-source-c9a97c501c718b62) | Intersection of fitted slopes around a magnetic cusp | A different protocol from Figure 4; no automatic zero-resistance interpretation |
| Bhatt SLAO film passage [R4](#ref-source-4b5b65a5047eb1a9) | Resistive onset near 42 K and zero near 2 K | Broad transition in a film; two endpoints are separate records |
| Ko A1 field analysis [R5](#ref-source-98849f3ad0a2df49) | 90% of normal-state resistance near onset | Separate from zero resistance and from sample A12 magnetic response |
| Ko 2026 correction [R6](#ref-source-acee7fe0af86cc44) | Resistivity units and a temperature-axis label | Publication correction, not a new transition or a retraction |

## Limits and disputes

Bhatt's films on SLAO used pulsed-laser deposition, whereas the other substrate films used molecular-beam epitaxy. Oxygen annealing and uncertain oxygen occupancy remain relevant covariates. Figure 3 supports out-of-plane expansion under in-plane compression, contrasting with hydrostatic contraction. It does not support the inherited universal superlative that the SLAO film has the largest c-axis: the plotted LAO values are comparable or higher. Avoid turning a qualitative structural contrast into an unsupported ranking. [R4](#ref-source-4b5b65a5047eb1a9)

A peak near a calculated Lifshitz transition constrains possible models without uniquely identifying pairing symmetry. Steppke's electronic-structure and order-parameter calculations are model-dependent; their discussion should not be read as a present-day determination of Sr2RuO4's order parameter. This scoped review checked selected experimental passages and a figure, not the full multiband calculation, all supplements or experimental raw data. [R3](#ref-source-c9a97c501c718b62)

## Discovery implications

Design a strain study around a measured mechanical path and a defined superconducting criterion. Retain loading direction, reference state, adhesive or substrate constraints, thermal history and reversibility. Check whether a broadened transition tracks strain inhomogeneity or a changed specimen, and compare transport with magnetic or thermodynamic evidence where feasible. Local arithmetic here verifies mismatch, ideal elastic identities and the adhesive model; it neither predicts a superconducting transition nor establishes a unique strain mechanism. [R1](#ref-source-363388aa03563c00) [R3](#ref-source-c9a97c501c718b62) [R4](#ref-source-4b5b65a5047eb1a9)

## Related topics

Compare [pressure tuning](/scwiki/pressure-tuning), [chemical doping](/scwiki/chemical-doping), [electrostatic gating](/scwiki/electrostatic-gating), [nickelates](/scwiki/nickelates) and [two-dimensional interfaces](/scwiki/two-dimensional-interfaces).

## Material cases

Values describe individual reports, not a ranking. Unknown means the checked source did not supply the field at this review scope.

| Material and sample | Reported temperature | Criterion | Probe | Pressure | State | Evidence |
|---|---|---|---|---|---|---|
| Sr2RuO4; Steppke representative peak under approximately 0.6% a-axis compression | 3.4 K; Representative magnetic midpoint, not resistive zero or universal maximum. Thermodynamic equilibrium is not established by the selected report. | transition; magnetic-susceptibility-50-percent | Mutual inductance | unknown; unknown GPa | unknown | experiment; [source](#ref-source-c9a97c501c718b62) |
| Sr2RuO4; Steppke sample 5 peak | 3.5 K; Approximate sample 5 peak; strain scale normalized in Figure 4. Not a hydrostatic-pressure record. Thermodynamic equilibrium is not established by the selected report. | transition; magnetic-susceptibility-50-percent | Mutual inductance | unknown; unknown GPa | unknown | experiment; [source](#ref-source-c9a97c501c718b62) |
| La3Ni2O7 (aliases: nickelate, nickelates); SLAO thin film; Bhatt final-journal passage citing Ko | 42 K; Approximate onset; exact original operational onset algorithm not independently reviewed. Film geometry,not bulk. Thermodynamic equilibrium is not established by the selected report. | transition; resistive-onset | Resistivity | ambient; unknown GPa | unknown | experiment; [source](#ref-source-4b5b65a5047eb1a9) |
| La3Ni2O7 (aliases: nickelate, nickelates); SLAO thin film; Bhatt final-journal passage citing Ko | 2 K; Approximate zero-resistance endpoint, distinct from42Konset. Does not reproduce raw measurement uncertainty. Thermodynamic equilibrium is not established by the selected report. | transition; zero-resistance | Resistivity | ambient; unknown GPa | unknown | experiment; [source](#ref-source-4b5b65a5047eb1a9) |
| La3Ni2O7 (aliases: Ko A1, nickelate, nickelates); Ko A1 ozone-annealed SLAO thin film; archived author manuscript | 42.4 K; Source-reported onset, not a 90% or zero-resistance value. The separate zero-resistance statement below 2.2 K is a bound, not an exact transition assigned here. A12 magnetic evidence comes from another specimen. Final-version comparison and thermodynamic equilibrium remain unverified. | transition; resistive-onset | Resistivity | ambient; unknown GPa | unknown | experiment; [source](#ref-source-98849f3ad0a2df49) |

## Sources

### Ref source-363388aa03563c00

[R1] Piezoelectric-based apparatus for strain tuning (2014). [DOI 10.1063/1.4881611](https://doi.org/10.1063/1.4881611). Publication: journal-article. Check: selected-author-apparatus-and-adhesive-model. Checked: 2026-10-20. Author v2 revised 8 August 2014. Selected pp. 2–3 and Appendix A pp. 6–7 read; p. 7 visually inspected. Ideal uniaxial stress permits transverse Poisson strains. The printed parameters reproduce about 87 micrometres but give 1.74%/105 MPa for Eq. A1, unlike the adjacent 1.3%/80 MPa prose. This discrepancy is retained without claiming an erratum. No final-version comparison, glue-strength certification or finite-element replication.
### Ref source-2c98c9257f2c4d46

[R2] Strong Increase of Tc of Sr2RuO4 Under Both Tensile and Compressive Strain (2014). [DOI 10.1126/science.1248292](https://doi.org/10.1126/science.1248292). Publication: journal-article. Check: author-institution-abstract-only. Checked: 2026-10-18. Issue18April2014. Authors institutional abstract supports directional responses and0.23percent range. Full methods and curves not reviewed.
### Ref source-c9a97c501c718b62

[R3] Strong peak in Tc of Sr2RuO4 under uniaxial pressure (2017). [DOI 10.1126/science.aaf9398](https://doi.org/10.1126/science.aaf9398). Publication: journal-article. Check: selected-accepted-author-methods-and-figure. Checked: 2026-10-20. Accepted author v2 revised 14 December 2016; journal publication 13 January 2017. Selected pp. 6–8 and Figure 4 on p. 32 reread; figure visually inspected. Figure 4 uses a magnetic 50% midpoint, with 20–80% width and normalized strain scales. Sample 4 field scans instead use intersections around a cusp. Sample 5's 3.5 K peak, contacted samples 3/5 and broken sample 1 remain distinct. No complete supplement, final comparison, raw-data or equilibrium certification.
### Ref source-4b5b65a5047eb1a9

[R4] Structural modifications in strain-engineered bilayer nickelate thin films (2026). [DOI 10.1038/s41586-026-10446-2](https://doi.org/10.1038/s41586-026-10446-2). Publication: journal-article. Check: selected-final-journal-figures-and-methods. Checked: 2026-10-18. Online1April2026,issue7May. Selected final pp2,4,8 and Figs1/3 visually checked. Final measured labels differ from inherited draft. Growth-method/oxygen covariates and c-axis contrast retained. Complete supplement and raw-data analysis remain open.
### Ref source-98849f3ad0a2df49

[R5] Signatures of ambient pressure superconductivity in thin film La3Ni2O7 (2025). [DOI 10.1038/s41586-024-08525-3](https://doi.org/10.1038/s41586-024-08525-3). Publication: journal-article. Check: selected-publicly-archived-author-manuscript-and-correction-comparison. Checked: 2026-10-20. Public 34-page author manuscript downloaded; review covers selected pp. 3–4, 11–13 and Figures 1/3 on pp. 20/22, both visually inspected. A1 onset is 42.4 K and zero resistance is reported below 2.2 K. Field analysis uses a 90% resistance criterion; A12 magnetic evidence is separate. Approximately 100 kHz filtering is described. Author Figure 3 has mΩ cm but still labels its horizontal axis Tc; the final 2026 correction specifies T. No complete final/supplement comparison, raw fit or noise-threshold calibration.
### Ref source-acee7fe0af86cc44

[R6] Author Correction: Signatures of ambient pressure superconductivity in thin film La3Ni2O7 (2026). [DOI 10.1038/s41586-026-10335-8](https://doi.org/10.1038/s41586-026-10335-8). Publication: journal-article. Check: complete-correction-text. Checked: 2026-10-20. Complete one-page correction reread. Published 31 March 2026; issue 16 April. Corrected journal resistivity units are mΩ cm and the Figure 3d horizontal variable is T. The archived author figure already has the corrected resistivity unit but still shows Tc horizontally; it is not a verified corrected final version. Not a retraction or a new transition measurement.

## Claim evidence and conditions

### scwiki-e4-claim-scope-1

Strain is a directional deformation relative to a stated reference structure. A uniaxially loaded crystal, a clamped epitaxial film and a hydrostatically compressed sample follow different mechanical paths. Applied displacement is not necessarily sample strain: mounting adhesive, thermal contraction, bending and fracture can all intervene. The useful control variable is the calibrated deformation in the region probed, together with its uncertainty and history. In the ideal uniaxial-stress geometry, transverse Poisson strains remain nonzero: controlling one loading axis does not set every other strain component to zero. A displacement sensor also does not directly measure the strain throughout a specimen.

Evidence: experiment. Sources: source-363388aa03563c00, source-c9a97c501c718b62.

Source relationship: context-for-editorial-analysis. Selected source passages support the reported apparatus and observations; recommendations and comparisons are scoped editorial analysis.

Conditions: Retain source version, specimen, reference state, mechanical boundary condition and probe-specific transition criterion. Unknown equilibrium does not establish nonequilibrium.

Verification scope: Named selected primary passages/figures and bounded elastic arithmetic; full scientific acceptance remains open.

### scwiki-e4-claim-scope-2

Separate the early Sr2RuO4 experiments. Hicks's 2014 Science study reported different responses for loading along the crystallographic ⟨100⟩ and ⟨110⟩ directions, within an approximately 0.23% accessible range. The later Steppke study reached the much larger compressive strain associated with a transition near 3.4 K. These are distinct measurements, not interchangeable references for one apparatus or peak. The earlier result is checked here only through the authors' institutional abstract.

Evidence: experiment. Sources: source-2c98c9257f2c4d46, source-c9a97c501c718b62.

Source relationship: context-for-editorial-analysis. Selected source passages support the reported apparatus and observations; recommendations and comparisons are scoped editorial analysis.

Conditions: Retain source version, specimen, reference state, mechanical boundary condition and probe-specific transition criterion. Unknown equilibrium does not establish nonequilibrium.

Verification scope: Named selected primary passages/figures and bounded elastic arithmetic; full scientific acceptance remains open.

### scwiki-e4-claim-mathematical-assumptions-1

For a lattice parameter relative to a relaxed reference, engineering strain is $\epsilon=(a-a_0)/a_0$. Nominal epitaxial mismatch uses $f=(a_{\rm sub}-a_{\rm ref})/a_{\rm ref}$ instead. Neither a substrate name nor this calculation establishes the strain remaining after relaxation. Report reference composition, phase, temperature and orientation; compare actual film lattice parameters with that same reference.

Evidence: theory. Sources: source-4b5b65a5047eb1a9.

Source relationship: mixed-source-and-local-derivation. Source equations and parameters are distinguished from local arithmetic; no material calibration or empirical fit is implied.

Conditions: Retain source version, specimen, reference state, mechanical boundary condition and probe-specific transition criterion. Unknown equilibrium does not establish nonequilibrium.

Verification scope: Named selected primary passages/figures and bounded elastic arithmetic; full scientific acceptance remains open.

### scwiki-e4-claim-mathematical-assumptions-2

In small-deformation elasticity, $\epsilon_{ij}=(\partial_i u_j+\partial_j u_i)/2$ and $\sigma_{ij}=C_{ijkl}\epsilon_{kl}$. As an explicitly isotropic illustration, a film with equal in-plane strains $\epsilon_{xx}=\epsilon_{yy}=f$ and a traction-free surface has $\epsilon_{zz}=-2\nu f/(1-\nu)$. Positive Poisson ratio therefore permits out-of-plane expansion under in-plane compression. This illustration is not an anisotropic nickelate fit, and it does not convert epitaxial mismatch into an equivalent hydrostatic pressure.

Evidence: theory. Sources: source-363388aa03563c00, source-4b5b65a5047eb1a9.

Source relationship: mixed-source-and-local-derivation. Source equations and parameters are distinguished from local arithmetic; no material calibration or empirical fit is implied.

Conditions: Retain source version, specimen, reference state, mechanical boundary condition and probe-specific transition criterion. Unknown equilibrium does not establish nonequilibrium.

Verification scope: Named selected primary passages/figures and bounded elastic arithmetic; full scientific acceptance remains open.

### scwiki-e4-claim-mathematical-assumptions-3

Hicks's simplified adhesive model gives a load-transfer length $\lambda=\sqrt{Etd/(nG_e)}$, with sample Young's modulus $E$, sample thickness $t$, adhesive thickness $d$, adhesive shear modulus $G_e$, and one or two bonded faces $n$. For symmetric ends, displacement is distributed over approximately $L+2\lambda$, not just the exposed length $L$. With $E=182$ GPa, $t=50$ micrometres, $d=10$ micrometres, $n=2$ and $G_e=6$ GPa, the model gives 87 micrometres, consistent with the paper's approximately 90 micrometres. For an illustrative 1 mm exposed length, dividing displacement by $L$ alone overestimates the model's central strain by about 17% relative to that strain. This is local arithmetic, not a recalibration of Steppke's samples. Rigid plates, much softer adhesive, long bonded regions and uniform strain across the sample cross-section are assumptions.

Evidence: theory. Sources: source-363388aa03563c00.

Source relationship: mixed-source-and-local-derivation. Source equations and parameters are distinguished from local arithmetic; no material calibration or empirical fit is implied.

Conditions: Retain source version, specimen, reference state, mechanical boundary condition and probe-specific transition criterion. Unknown equilibrium does not establish nonequilibrium.

Verification scope: Named selected primary passages/figures and bounded elastic arithmetic; full scientific acceptance remains open.

### scwiki-e4-claim-experimental-criteria-1

Steppke measured magnetic transitions using mutual inductance, with approximately 0.2 Oe excitation at 1–20 kHz, and used a capacitive displacement sensor. Figure 4 defines the plotted transition temperatures at 50% of the magnetic response; the 20% and 80% levels show transition width. The reported peak strain is approximately −0.60% with a ±0.06 percentage-point uncertainty from four samples, while individual strain calibration was estimated to have roughly 20% uncertainty. These are different uncertainty statements.

Evidence: experiment. Sources: source-c9a97c501c718b62.

Source relationship: direct-support. Selected original passages support only the stated specimen, probe and criterion; final/supplement/raw-data review remains bounded.

Conditions: Retain source version, specimen, reference state, mechanical boundary condition and probe-specific transition criterion. Unknown equilibrium does not establish nonequilibrium.

Verification scope: Named selected primary passages/figures and bounded elastic arithmetic; full scientific acceptance remains open.

### scwiki-e4-claim-experimental-criteria-2

The often-quoted 3.4 K scale is not a universal sample maximum: sample 5 reached approximately 3.5 K. Resistive transitions in the two contacted specimens did not exceed the highest magnetic transition by more than 0.08 K. That comparison does not redefine a magnetic midpoint as zero resistance. A flat feature near zero strain in sample 1 arose after the sample broke during cooling and needed compression to re-engage; it should not be fitted as an intrinsic phase boundary. Reported recovery of magnetic curves after unloading other checks supports reversible deformation under those conditions, not a guarantee that every mounting survives or that thermodynamic equilibrium has been established. The critical-field measurements on sample 4 use intersections of linear fits around a susceptibility cusp; that separate procedure must not replace the 50% criterion for the Figure 4 temperature-versus-strain data.

Evidence: experiment. Sources: source-c9a97c501c718b62.

Source relationship: direct-support. Selected original passages support only the stated specimen, probe and criterion; final/supplement/raw-data review remains bounded.

Conditions: Retain source version, specimen, reference state, mechanical boundary condition and probe-specific transition criterion. Unknown equilibrium does not establish nonequilibrium.

Verification scope: Named selected primary passages/figures and bounded elastic arithmetic; full scientific acceptance remains open.

### scwiki-e4-claim-experimental-criteria-3

Bhatt's final Figure 1 labels nominal/measured mismatch pairs, respectively, as SLAO −2.0%/−1.6%, LAO −1.2%/−0.9%, NGO +0.7%/+0.6% and STO +1.9%/+1.8%. These final labels replace several different measured values in the inherited chapter. The SLAO film has a broad resistive transition, with onset near 42 K and zero near 2 K; those endpoints cannot be merged into a 42 K zero-resistance claim.

Evidence: experiment. Sources: source-4b5b65a5047eb1a9.

Source relationship: direct-support. Selected original passages support only the stated specimen, probe and criterion; final/supplement/raw-data review remains bounded.

Conditions: Retain source version, specimen, reference state, mechanical boundary condition and probe-specific transition criterion. Unknown equilibrium does not establish nonequilibrium.

Verification scope: Named selected primary passages/figures and bounded elastic arithmetic; full scientific acceptance remains open.

### scwiki-e4-claim-experimental-criteria-4

Ko's publicly archived author manuscript now supplies selected original methods and criteria. It reports sample A1 with onset at 42.4 K and zero resistance below 2.2 K; the latter is not an exact 2.2 K transition value. Its field-dependent analysis instead uses 90% of the normal-state resistance near onset. The methods describe approximately 100 kHz low-pass filtering; the text warns that observing zero resistance requires adequate radiation filtering. The reported diamagnetic response belongs to sample A12, so it must not be attached to A1 as a same-specimen measurement. The March 2026 correction fixes published resistivity-axis units to mΩ cm and the Figure 3d horizontal label to temperature $T$, not $T_c$. The archived manuscript already has mΩ cm but still labels that axis $T_c$; it is not a verified copy of the corrected journal version. Existing rounded film records retain Bhatt's final passage, while the added A1 onset record cites the author manuscript. No raw-data refit or full final-version comparison is claimed.

Evidence: experiment. Sources: source-4b5b65a5047eb1a9, source-98849f3ad0a2df49, source-acee7fe0af86cc44.

Source relationship: direct-support. Selected original passages support only the stated specimen, probe and criterion; final/supplement/raw-data review remains bounded.

Conditions: Retain source version, specimen, reference state, mechanical boundary condition and probe-specific transition criterion. Unknown equilibrium does not establish nonequilibrium.

Verification scope: Named selected primary passages/figures and bounded elastic arithmetic; full scientific acceptance remains open.

### scwiki-e4-claim-limits-and-disputes-1

Bhatt's films on SLAO used pulsed-laser deposition, whereas the other substrate films used molecular-beam epitaxy. Oxygen annealing and uncertain oxygen occupancy remain relevant covariates. Figure 3 supports out-of-plane expansion under in-plane compression, contrasting with hydrostatic contraction. It does not support the inherited universal superlative that the SLAO film has the largest c-axis: the plotted LAO values are comparable or higher. Avoid turning a qualitative structural contrast into an unsupported ranking.

Evidence: experiment. Sources: source-4b5b65a5047eb1a9.

Source relationship: context-for-editorial-analysis. Selected source passages support the reported apparatus and observations; recommendations and comparisons are scoped editorial analysis.

Conditions: Retain source version, specimen, reference state, mechanical boundary condition and probe-specific transition criterion. Unknown equilibrium does not establish nonequilibrium.

Verification scope: Named selected primary passages/figures and bounded elastic arithmetic; full scientific acceptance remains open.

### scwiki-e4-claim-limits-and-disputes-2

A peak near a calculated Lifshitz transition constrains possible models without uniquely identifying pairing symmetry. Steppke's electronic-structure and order-parameter calculations are model-dependent; their discussion should not be read as a present-day determination of Sr2RuO4's order parameter. This scoped review checked selected experimental passages and a figure, not the full multiband calculation, all supplements or experimental raw data.

Evidence: experiment. Sources: source-c9a97c501c718b62.

Source relationship: context-for-editorial-analysis. Selected source passages support the reported apparatus and observations; recommendations and comparisons are scoped editorial analysis.

Conditions: Retain source version, specimen, reference state, mechanical boundary condition and probe-specific transition criterion. Unknown equilibrium does not establish nonequilibrium.

Verification scope: Named selected primary passages/figures and bounded elastic arithmetic; full scientific acceptance remains open.

### scwiki-e4-claim-discovery-implications-1

Design a strain study around a measured mechanical path and a defined superconducting criterion. Retain loading direction, reference state, adhesive or substrate constraints, thermal history and reversibility. Check whether a broadened transition tracks strain inhomogeneity or a changed specimen, and compare transport with magnetic or thermodynamic evidence where feasible. Local arithmetic here verifies mismatch, ideal elastic identities and the adhesive model; it neither predicts a superconducting transition nor establishes a unique strain mechanism.

Evidence: theory. Sources: source-363388aa03563c00, source-c9a97c501c718b62, source-4b5b65a5047eb1a9.

Source relationship: context-for-editorial-analysis. Selected source passages support the reported apparatus and observations; recommendations and comparisons are scoped editorial analysis.

Conditions: Retain source version, specimen, reference state, mechanical boundary condition and probe-specific transition criterion. Unknown equilibrium does not establish nonequilibrium.

Verification scope: Named selected primary passages/figures and bounded elastic arithmetic; full scientific acceptance remains open.

### scwiki-e4-claim-mathematical-assumptions-4

The same author manuscript's Appendix A contains a numerical discrepancy worth preserving. Using its printed Eq. A1 and the parameters above, a 0.2% sample strain gives a displacement-over-glue-thickness shear of approximately 1.74% and a shear stress of 105 MPa; the adjacent prose instead reports 1.3% and 80 MPa. The scalar shear here follows that equation's convention, not the half-sized off-diagonal strain-tensor component. This substitution check does not establish a formal correction or a failure threshold. The paper itself notes uncertain low-temperature adhesive properties; room-temperature tensile strength is not a measured cryogenic shear-strength limit.

Evidence: theory. Sources: source-363388aa03563c00.

Source relationship: mixed-source-and-local-derivation. Source equations and parameters are distinguished from local arithmetic; no material calibration or empirical fit is implied.

Conditions: Retain source version, specimen, reference state, mechanical boundary condition and probe-specific transition criterion. Unknown equilibrium does not establish nonequilibrium.

Verification scope: Named selected primary passages/figures and bounded elastic arithmetic; full scientific acceptance remains open.

## Revision and review

Article ID: scwiki-e4. Revision: e2cbe21b34ca82ff136a. Updated: 2026-10-19T18:47:38.003103+00:00.

Review scope: Selected Hicks author-v2 pp. 2–3 and 6–7, Steppke accepted-v2 pp. 6–8 and Figure 4, Bhatt final-journal passages, Ko archived author-manuscript pp. 3–4, 11–13 and Figures 1/3, plus the complete 2026 correction; bounded displacement and adhesive arithmetic.

- Complete scientific acceptance, remaining final-version comparisons, full supplements and raw-data reproduction remain open.
- Hicks's 2014 Science paper remains within institutional-abstract scope. Selected passages of Ko's author manuscript have now been read; its figures are not a verified copy of the corrected final journal version.
- Isotropic and ideal adhesive arithmetic does not calibrate real anisotropic specimens or cryogenic glue strength. The Hicks printed shear/stress example is not reproduced by its stated inputs.
- Onset, zero-resistance bounds, magnetic midpoints and critical-field fit criteria remain separate. Thermodynamic equilibrium has not been certified.

Source: [E_tuning_parameters/E4_strain.md](https://github.com/JackZH26/jzis-superconductivity/blob/0a7c9d6696804ec26aa12f8eed68b55c9b3c0fcf/E_tuning_parameters/E4_strain.md), commit 0a7c9d6696804ec26aa12f8eed68b55c9b3c0fcf, SHA-256 cf37f577788e1dc80462cb7daac3a80d34e9656910b6a6e879440554376b99ab.