# Linear-T resistivity: strange-metal evidence and model limits

Read linear-temperature transport with its fit window, field and carrier assumptions. Distinguish total resistivity, parallel conduction channels and inferred scattering rates.

## Scope

Linear-temperature resistivity describes a measured dependence over a specified range. The fit $\rho(T)=\rho_0+AT$ needs a sample, current direction, field, temperature interval and residuals. A straight-looking trace is not by itself evidence for a quantum critical point, a universal lifetime or a pairing interaction. This entry treats transport phenomenology; the linked Planckian entry discusses lifetime interpretations.

Separate a finite-field normal state, the region affected by superconducting fluctuations, and a higher-temperature regime that may have different scattering. Martin and colleagues' Bi-based crystal abstract reports strongly anisotropic transport; an in-plane trend is not an isotropic resistivity law. [R1](#ref-source-a5d6480d08ee8555)

## Mathematical assumptions

A least-squares slope depends on both the model and the sampled window. For exact synthetic data $\rho=r_0+aT+bT^2$, equally weighted temperatures symmetric about $\bar T$ give

$$A_{\mathrm{fit}}=a+2b\bar T.$$

This follows by inserting the quadratic into $\operatorname{cov}(T,\rho)/\operatorname{var}(T)$. A narrower interval can hide curvature while changing the inferred slope. Independent synthetic fits confirm this counterexample; they are not fits to any material. Experimental model comparison also needs uncertainties, correlations and a justified treatment of residuals.

For a single isotropic Drude channel with temperature-independent carrier density $n$ and mass $m^*$, an inelastic pole relaxation rate $\gamma=\alpha k_BT/\hbar$ gives $A=\alpha m^*k_B/(ne^2\hbar)$. Thus a slope fixes $\alpha$ only after the carrier parameters and response model are specified. If those parameters change with temperature, differentiating resistivity produces additional terms. This conditional connection underlies the selected Legros analysis. [R4](#ref-source-c1ae7869b672a8e8)

For a circular, parabolic two-dimensional band with total degeneracy $g$, use total sheet density $n_{2D}=gk_F^2/(4\pi)$ and $k_BT_F=\hbar^2k_F^2/(2m^*)$. The preceding Drude model then yields

$$A_{\square}T_F=\frac{\alpha h}{g e^2}.$$

The familiar factor of two corresponds to $g=2$, not an arbitrary multiband system. A bulk slope converted per conducting plane uses $A_{\square}=A/d$ with the stated effective plane spacing $d$. Independent occupied-disk and algebra checks cover $g=1,2,4$; neither degeneracy nor a mass should be transferred between materials without justification.

Parallel channels add conductivities. As an independent scalar, zero-field example, let $r(T)=r_0+aT>0$ describe one channel and let $\sigma_b\ge0$ be a constant background conductivity in matching units. Then

$$\rho_{\mathrm{tot}}=\frac{r(T)}{1+\sigma_b r(T)},\qquad\frac{d\rho_{\mathrm{tot}}}{dT}=\frac{a}{[1+\sigma_b r(T)]^2}.$$

The total slope is generally temperature dependent even though the first channel's resistance is exactly linear. Nine numerical derivative checks verify this model. It is not a multiband fit; in magnetic field, conductivity tensors must be added before inversion. Adding scattering mechanisms within one channel is a different assumption from adding parallel conductivities.

## Experimental criteria

Legros and colleagues' earlier manuscript measures a Bi2212 film with nominal hole doping 0.23 in pulsed fields. Its 55 T trace and magnetoresistance-corrected, extrapolated zero-field curve are distinct datasets. The analysis estimates carrier parameters and geometric uncertainty; the checked passages do not turn its interpretation into a model-independent universal bound. [R4](#ref-source-c1ae7869b672a8e8)

Cao and colleagues measure four-probe transport in gated twisted bilayer graphene. Their linear regime depends on filling and a crossover temperature. The operational scattering coefficient uses density and mass from low-temperature quantum oscillations; those assumptions matter when interpreting higher-temperature transport. The selected passages do not establish one shared microscopic mechanism across material families. [R5](#ref-source-8135909144b6b16b)

Romero and colleagues' earlier manuscript studies two 100 nm FeTe1-xSex films, x = 0.45 and 0.35, over 0.2–3 THz. Its narrow-channel fits use 20–40 K and report coefficients 3.02 and 2.42 in $\Gamma=\Gamma_0+\alpha k_BT/h$. These are channel-specific fit results, not coefficients of the total DC resistivity. [R6](#ref-source-05b2d5ff6757b5eb)

Record the raw voltage/current or conductivity data, geometry, composition, field direction, fit interval and uncertainty model. Identify excluded transition regions and test alternative fit windows and curvature. A successful fit does not establish that its parameters are uniquely identifiable. Normal-state measurement temperatures remain separate from superconducting transition temperatures in the records below.

## Limits and disputes

Frequency conventions can create a factor-of-$2\pi$ error. For a Drude denominator $\Gamma-i\nu$ with ordinary frequency $\nu$, the corresponding pole rate is $\gamma=1/\tau=2\pi\Gamma$ in a denominator $\gamma-i\omega$, where $\omega=2\pi\nu$. Consequently $\Gamma=\alpha k_BT/h$ converts to $\gamma=\alpha k_BT/\hbar$. State the denominator and linewidth convention before comparing coefficients. This is a convention check, not a new measurement of a lifetime.

A shared temperature exponent does not identify a unique microscopic interaction. Drude transport, optical fits and single-particle lifetimes measure or infer different quantities. Extrapolating carrier parameters, suppressing superconductivity by field, or neglecting a parallel channel can affect an inferred coefficient. Report these choices alongside any claimed universality rather than treating the fit exponent as a proof.

Cooper's LSCO study and Bruin's cross-metal comparison remain bibliographic starting points here. Their complete datasets and numerical conclusions have not been reanalyzed in this entry. Selected manuscript checks above also leave final-version comparison and full uncertainty reproduction open. [R2](#ref-source-1610fd228e679225) [R3](#ref-source-e6d342432f3409ae)

## Discovery implications

Use linear-T transport to organize experiments, not to rank superconductors or predict a transition temperature by itself. A stronger comparison holds sample state, probe definition and fitting procedure fixed, then asks whether independent optical, thermodynamic or quantum-oscillation information supports the same parameter interpretation. Retain counterexamples and failed fits; correlation with superconductivity does not identify its cause.

## Related topics

Continue with [Planckian dissipation](/scwiki/planckian-dissipation), [zero resistance](/scwiki/zero-resistance), [critical fields](/scwiki/critical-fields), [specific heat](/scwiki/specific-heat-jump), [cuprates](/scwiki/cuprates), and [multiband pairing](/scwiki/multiband-pairing).

## 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 |
|---|---|---|---|---|---|---|
| Bi2Sr2CaCu2O8+delta (aliases: cuprate, cuprates); Legros v1 Bi2212 film; nominal p = 0.23 | Normal-state transport or fit interval; no equilibrium Tc assigned here | normal-state; normal-state-transport | Six-point transport in pulsed fields; 55 T trace and magnetoresistance-corrected extrapolation distinguished | unknown; unknown GPa | unknown | experiment; [source](#ref-source-c1ae7869b672a8e8) |
| C; Cao gated twisted bilayer graphene; device and filling dependent | Normal-state transport or fit interval; no equilibrium Tc assigned here | normal-state; normal-state-transport | Four-probe longitudinal transport; low-temperature SdH carrier parameters used in operational rate estimate | unknown; unknown GPa | unknown | experiment; [source](#ref-source-8135909144b6b16b) |
| FeTe1-xSex (aliases: iron-based, iron based superconductors); Romero v1 films: x = 0.45 and 0.35; thickness 100 nm | Normal-state transport or fit interval; no equilibrium Tc assigned here | normal-state; normal-state-transport | 0.2–3 THz spectroscopy with DC constraint; narrow-channel 20–40 K fit; ordinary-frequency rate | unknown; unknown GPa | unknown | experiment; [source](#ref-source-05b2d5ff6757b5eb) |

## Sources

### Ref source-a5d6480d08ee8555

[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.
### Ref source-1610fd228e679225

[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: crossref-metadata-only. Checked: 2026-10-18. Bibliographic identity only in A8. No numerical result or complete experimental claim extracted.
### Ref source-e6d342432f3409ae

[R3] Similarity of Scattering Rates in Metals Showing T-Linear Resistivity (2013). [DOI 10.1126/science.1227612](https://doi.org/10.1126/science.1227612). Publication: journal-article. Check: crossref-metadata-only. Checked: 2026-10-18. Bibliographic identity only in A8. Cross-material numerical comparisons not reproduced.
### Ref source-c1ae7869b672a8e8

[R4] 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.
### Ref source-8135909144b6b16b

[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.
### Ref source-05b2d5ff6757b5eb

[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: earlier-author-manuscript-scoped-check. Checked: 2026-10-18. Selected v1 Fig. 1–3 discussion: films, spectral range, fit window and frequency convention. Publisher identity checked; complete final-version comparison and fit reproduction remain open.

## Claim evidence and conditions

### scwiki-a8-claim-scope-1

Linear-temperature resistivity describes a measured dependence over a specified range. The fit $\rho(T)=\rho_0+AT$ needs a sample, current direction, field, temperature interval and residuals. A straight-looking trace is not by itself evidence for a quantum critical point, a universal lifetime or a pairing interaction. This entry treats transport phenomenology; the linked Planckian entry discusses lifetime interpretations.

Evidence: hypothesis. Sources: source-8135909144b6b16b.

Conditions: Editorial reporting and inference criteria; no universal lifetime, pairing mechanism or transition temperature follows from a fitted slope.

Verification scope: Pinned A8 chapter edited with explicit source/model limitations.

### scwiki-a8-claim-scope-2

Separate a finite-field normal state, the region affected by superconducting fluctuations, and a higher-temperature regime that may have different scattering. Martin and colleagues' Bi-based crystal abstract reports strongly anisotropic transport; an in-plane trend is not an isotropic resistivity law.

Evidence: experiment. Sources: source-a5d6480d08ee8555.

Conditions: Sample-, probe-, field-, fit-window- and version-specific observations; no material-independent coefficient or new equilibrium Tc record.

Verification scope: Selected primary passages as specified by the cited reference; no raw-data reproduction.

### scwiki-a8-claim-mathematical-assumptions-1

A least-squares slope depends on both the model and the sampled window. For exact synthetic data $\rho=r_0+aT+bT^2$, equally weighted temperatures symmetric about $\bar T$ give

Evidence: theory. Sources: source-c1ae7869b672a8e8.

Source relationship: context-for-local-derivation. Legros v1 p. 4 supplies the isotropic Drude relation and its twofold-degenerate 2D expression. Explicit total-degeneracy counting, fitting-window examples and the parallel-channel counterexample are local conditional derivations; they are not fitted results from that paper.

Conditions: Conditional local models: symmetric equal-weight quadratic fit; single isotropic constant-parameter Drude channel; circular parabolic 2D band with explicit degeneracy; scalar zero-field parallel conductance; stated frequency denominator.

Verification scope: Independent synthetic/algebra/finite-difference checks, not experimental calibration or original dataset fitting.

### scwiki-a8-claim-mathematical-assumptions-2

$$A_{\mathrm{fit}}=a+2b\bar T.$$

Evidence: theory. Sources: source-c1ae7869b672a8e8.

Source relationship: context-for-local-derivation. Legros v1 p. 4 supplies the isotropic Drude relation and its twofold-degenerate 2D expression. Explicit total-degeneracy counting, fitting-window examples and the parallel-channel counterexample are local conditional derivations; they are not fitted results from that paper.

Conditions: Conditional local models: symmetric equal-weight quadratic fit; single isotropic constant-parameter Drude channel; circular parabolic 2D band with explicit degeneracy; scalar zero-field parallel conductance; stated frequency denominator.

Verification scope: Independent synthetic/algebra/finite-difference checks, not experimental calibration or original dataset fitting.

### scwiki-a8-claim-mathematical-assumptions-3

This follows by inserting the quadratic into $\operatorname{cov}(T,\rho)/\operatorname{var}(T)$. A narrower interval can hide curvature while changing the inferred slope. Independent synthetic fits confirm this counterexample; they are not fits to any material. Experimental model comparison also needs uncertainties, correlations and a justified treatment of residuals.

Evidence: theory. Sources: source-c1ae7869b672a8e8.

Source relationship: context-for-local-derivation. Legros v1 p. 4 supplies the isotropic Drude relation and its twofold-degenerate 2D expression. Explicit total-degeneracy counting, fitting-window examples and the parallel-channel counterexample are local conditional derivations; they are not fitted results from that paper.

Conditions: Conditional local models: symmetric equal-weight quadratic fit; single isotropic constant-parameter Drude channel; circular parabolic 2D band with explicit degeneracy; scalar zero-field parallel conductance; stated frequency denominator.

Verification scope: Independent synthetic/algebra/finite-difference checks, not experimental calibration or original dataset fitting.

### scwiki-a8-claim-mathematical-assumptions-4

For a single isotropic Drude channel with temperature-independent carrier density $n$ and mass $m^*$, an inelastic pole relaxation rate $\gamma=\alpha k_BT/\hbar$ gives $A=\alpha m^*k_B/(ne^2\hbar)$. Thus a slope fixes $\alpha$ only after the carrier parameters and response model are specified. If those parameters change with temperature, differentiating resistivity produces additional terms. This conditional connection underlies the selected Legros analysis.

Evidence: theory. Sources: source-c1ae7869b672a8e8.

Source relationship: mixed-source-and-local-derivation. Legros v1 p. 4 supplies the isotropic Drude relation and its twofold-degenerate 2D expression. Explicit total-degeneracy counting, fitting-window examples and the parallel-channel counterexample are local conditional derivations; they are not fitted results from that paper.

Conditions: Conditional local models: symmetric equal-weight quadratic fit; single isotropic constant-parameter Drude channel; circular parabolic 2D band with explicit degeneracy; scalar zero-field parallel conductance; stated frequency denominator.

Verification scope: Independent synthetic/algebra/finite-difference checks, not experimental calibration or original dataset fitting.

### scwiki-a8-claim-mathematical-assumptions-5

For a circular, parabolic two-dimensional band with total degeneracy $g$, use total sheet density $n_{2D}=gk_F^2/(4\pi)$ and $k_BT_F=\hbar^2k_F^2/(2m^*)$. The preceding Drude model then yields

Evidence: theory. Sources: source-c1ae7869b672a8e8.

Source relationship: mixed-source-and-local-derivation. Legros v1 p. 4 supplies the isotropic Drude relation and its twofold-degenerate 2D expression. Explicit total-degeneracy counting, fitting-window examples and the parallel-channel counterexample are local conditional derivations; they are not fitted results from that paper.

Conditions: Conditional local models: symmetric equal-weight quadratic fit; single isotropic constant-parameter Drude channel; circular parabolic 2D band with explicit degeneracy; scalar zero-field parallel conductance; stated frequency denominator.

Verification scope: Independent synthetic/algebra/finite-difference checks, not experimental calibration or original dataset fitting.

### scwiki-a8-claim-mathematical-assumptions-6

$$A_{\square}T_F=\frac{\alpha h}{g e^2}.$$

Evidence: theory. Sources: source-c1ae7869b672a8e8.

Source relationship: mixed-source-and-local-derivation. Legros v1 p. 4 supplies the isotropic Drude relation and its twofold-degenerate 2D expression. Explicit total-degeneracy counting, fitting-window examples and the parallel-channel counterexample are local conditional derivations; they are not fitted results from that paper.

Conditions: Conditional local models: symmetric equal-weight quadratic fit; single isotropic constant-parameter Drude channel; circular parabolic 2D band with explicit degeneracy; scalar zero-field parallel conductance; stated frequency denominator.

Verification scope: Independent synthetic/algebra/finite-difference checks, not experimental calibration or original dataset fitting.

### scwiki-a8-claim-mathematical-assumptions-7

The familiar factor of two corresponds to $g=2$, not an arbitrary multiband system. A bulk slope converted per conducting plane uses $A_{\square}=A/d$ with the stated effective plane spacing $d$. Independent occupied-disk and algebra checks cover $g=1,2,4$; neither degeneracy nor a mass should be transferred between materials without justification.

Evidence: theory. Sources: source-c1ae7869b672a8e8.

Source relationship: mixed-source-and-local-derivation. Legros v1 p. 4 supplies the isotropic Drude relation and its twofold-degenerate 2D expression. Explicit total-degeneracy counting, fitting-window examples and the parallel-channel counterexample are local conditional derivations; they are not fitted results from that paper.

Conditions: Conditional local models: symmetric equal-weight quadratic fit; single isotropic constant-parameter Drude channel; circular parabolic 2D band with explicit degeneracy; scalar zero-field parallel conductance; stated frequency denominator.

Verification scope: Independent synthetic/algebra/finite-difference checks, not experimental calibration or original dataset fitting.

### scwiki-a8-claim-mathematical-assumptions-8

Parallel channels add conductivities. As an independent scalar, zero-field example, let $r(T)=r_0+aT>0$ describe one channel and let $\sigma_b\ge0$ be a constant background conductivity in matching units. Then

Evidence: theory. Sources: source-c1ae7869b672a8e8.

Source relationship: context-for-local-derivation. Legros v1 p. 4 supplies the isotropic Drude relation and its twofold-degenerate 2D expression. Explicit total-degeneracy counting, fitting-window examples and the parallel-channel counterexample are local conditional derivations; they are not fitted results from that paper.

Conditions: Conditional local models: symmetric equal-weight quadratic fit; single isotropic constant-parameter Drude channel; circular parabolic 2D band with explicit degeneracy; scalar zero-field parallel conductance; stated frequency denominator.

Verification scope: Independent synthetic/algebra/finite-difference checks, not experimental calibration or original dataset fitting.

### scwiki-a8-claim-mathematical-assumptions-9

$$\rho_{\mathrm{tot}}=\frac{r(T)}{1+\sigma_b r(T)},\qquad\frac{d\rho_{\mathrm{tot}}}{dT}=\frac{a}{[1+\sigma_b r(T)]^2}.$$

Evidence: theory. Sources: source-c1ae7869b672a8e8.

Source relationship: context-for-local-derivation. Legros v1 p. 4 supplies the isotropic Drude relation and its twofold-degenerate 2D expression. Explicit total-degeneracy counting, fitting-window examples and the parallel-channel counterexample are local conditional derivations; they are not fitted results from that paper.

Conditions: Conditional local models: symmetric equal-weight quadratic fit; single isotropic constant-parameter Drude channel; circular parabolic 2D band with explicit degeneracy; scalar zero-field parallel conductance; stated frequency denominator.

Verification scope: Independent synthetic/algebra/finite-difference checks, not experimental calibration or original dataset fitting.

### scwiki-a8-claim-mathematical-assumptions-10

The total slope is generally temperature dependent even though the first channel's resistance is exactly linear. Nine numerical derivative checks verify this model. It is not a multiband fit; in magnetic field, conductivity tensors must be added before inversion. Adding scattering mechanisms within one channel is a different assumption from adding parallel conductivities.

Evidence: theory. Sources: source-c1ae7869b672a8e8.

Source relationship: context-for-local-derivation. Legros v1 p. 4 supplies the isotropic Drude relation and its twofold-degenerate 2D expression. Explicit total-degeneracy counting, fitting-window examples and the parallel-channel counterexample are local conditional derivations; they are not fitted results from that paper.

Conditions: Conditional local models: symmetric equal-weight quadratic fit; single isotropic constant-parameter Drude channel; circular parabolic 2D band with explicit degeneracy; scalar zero-field parallel conductance; stated frequency denominator.

Verification scope: Independent synthetic/algebra/finite-difference checks, not experimental calibration or original dataset fitting.

### scwiki-a8-claim-experimental-criteria-1

Legros and colleagues' earlier manuscript measures a Bi2212 film with nominal hole doping 0.23 in pulsed fields. Its 55 T trace and magnetoresistance-corrected, extrapolated zero-field curve are distinct datasets. The analysis estimates carrier parameters and geometric uncertainty; the checked passages do not turn its interpretation into a model-independent universal bound.

Evidence: experiment. Sources: source-c1ae7869b672a8e8.

Conditions: Sample-, probe-, field-, fit-window- and version-specific observations; no material-independent coefficient or new equilibrium Tc record.

Verification scope: Selected primary passages as specified by the cited reference; no raw-data reproduction.

### scwiki-a8-claim-experimental-criteria-2

Cao and colleagues measure four-probe transport in gated twisted bilayer graphene. Their linear regime depends on filling and a crossover temperature. The operational scattering coefficient uses density and mass from low-temperature quantum oscillations; those assumptions matter when interpreting higher-temperature transport. The selected passages do not establish one shared microscopic mechanism across material families.

Evidence: experiment. Sources: source-8135909144b6b16b.

Conditions: Sample-, probe-, field-, fit-window- and version-specific observations; no material-independent coefficient or new equilibrium Tc record.

Verification scope: Selected primary passages as specified by the cited reference; no raw-data reproduction.

### scwiki-a8-claim-experimental-criteria-3

Romero and colleagues' earlier manuscript studies two 100 nm FeTe1-xSex films, x = 0.45 and 0.35, over 0.2–3 THz. Its narrow-channel fits use 20–40 K and report coefficients 3.02 and 2.42 in $\Gamma=\Gamma_0+\alpha k_BT/h$. These are channel-specific fit results, not coefficients of the total DC resistivity.

Evidence: experiment. Sources: source-05b2d5ff6757b5eb.

Conditions: Sample-, probe-, field-, fit-window- and version-specific observations; no material-independent coefficient or new equilibrium Tc record.

Verification scope: Selected primary passages as specified by the cited reference; no raw-data reproduction.

### scwiki-a8-claim-experimental-criteria-4

Record the raw voltage/current or conductivity data, geometry, composition, field direction, fit interval and uncertainty model. Identify excluded transition regions and test alternative fit windows and curvature. A successful fit does not establish that its parameters are uniquely identifiable. Normal-state measurement temperatures remain separate from superconducting transition temperatures in the records below.

Evidence: hypothesis. Sources: source-8135909144b6b16b.

Conditions: Editorial reporting and inference criteria; no universal lifetime, pairing mechanism or transition temperature follows from a fitted slope.

Verification scope: Pinned A8 chapter edited with explicit source/model limitations.

### scwiki-a8-claim-limits-and-disputes-1

Frequency conventions can create a factor-of-$2\pi$ error. For a Drude denominator $\Gamma-i\nu$ with ordinary frequency $\nu$, the corresponding pole rate is $\gamma=1/\tau=2\pi\Gamma$ in a denominator $\gamma-i\omega$, where $\omega=2\pi\nu$. Consequently $\Gamma=\alpha k_BT/h$ converts to $\gamma=\alpha k_BT/\hbar$. State the denominator and linewidth convention before comparing coefficients. This is a convention check, not a new measurement of a lifetime.

Evidence: theory. Sources: source-8135909144b6b16b.

Conditions: Conditional local models: symmetric equal-weight quadratic fit; single isotropic constant-parameter Drude channel; circular parabolic 2D band with explicit degeneracy; scalar zero-field parallel conductance; stated frequency denominator.

Verification scope: Independent synthetic/algebra/finite-difference checks, not experimental calibration or original dataset fitting.

### scwiki-a8-claim-limits-and-disputes-2

A shared temperature exponent does not identify a unique microscopic interaction. Drude transport, optical fits and single-particle lifetimes measure or infer different quantities. Extrapolating carrier parameters, suppressing superconductivity by field, or neglecting a parallel channel can affect an inferred coefficient. Report these choices alongside any claimed universality rather than treating the fit exponent as a proof.

Evidence: hypothesis. Sources: source-8135909144b6b16b.

Conditions: Editorial reporting and inference criteria; no universal lifetime, pairing mechanism or transition temperature follows from a fitted slope.

Verification scope: Pinned A8 chapter edited with explicit source/model limitations.

### scwiki-a8-claim-limits-and-disputes-3

Cooper's LSCO study and Bruin's cross-metal comparison remain bibliographic starting points here. Their complete datasets and numerical conclusions have not been reanalyzed in this entry. Selected manuscript checks above also leave final-version comparison and full uncertainty reproduction open.

Evidence: hypothesis. Sources: source-1610fd228e679225, source-e6d342432f3409ae.

Conditions: Editorial reporting and inference criteria; no universal lifetime, pairing mechanism or transition temperature follows from a fitted slope.

Verification scope: Pinned A8 chapter edited with explicit source/model limitations.

### scwiki-a8-claim-discovery-implications-1

Use linear-T transport to organize experiments, not to rank superconductors or predict a transition temperature by itself. A stronger comparison holds sample state, probe definition and fitting procedure fixed, then asks whether independent optical, thermodynamic or quantum-oscillation information supports the same parameter interpretation. Retain counterexamples and failed fits; correlation with superconductivity does not identify its cause.

Evidence: hypothesis. Sources: source-8135909144b6b16b.

Conditions: Editorial reporting and inference criteria; no universal lifetime, pairing mechanism or transition temperature follows from a fitted slope.

Verification scope: Pinned A8 chapter edited with explicit source/model limitations.

## Revision and review

Article ID: scwiki-a8. Revision: 5e7255f1fca8b8c1a2e3. Updated: 2026-10-19.

Review scope: Pinned A8 chapter; selected published Cao passages, Legros/Romero earlier manuscripts and Martin abstract; independent fit-window, Drude-degeneracy, parallel-channel and frequency-convention checks. Follow-up explicitly separates Legros v1 p. 4 from the local degeneracy and parallel-channel examples.

- Selected checks are not full scientific acceptance, experimental replication or complete uncertainty propagation.
- Legros and Romero earlier manuscript passages are version-specific; exhaustive comparison with final published articles remains open.
- Cooper and Bruin are bibliographic pointers only; no cross-family numerical alpha table reproduced.
- Synthetic model checks do not identify a material mechanism. No equilibrium Tc is inferred from normal-state transport.

Source: [A_phenomenology/A8_strange_metal_linear_T.md](https://github.com/JackZH26/jzis-superconductivity/blob/0a7c9d6696804ec26aa12f8eed68b55c9b3c0fcf/A_phenomenology/A8_strange_metal_linear_T.md), commit 0a7c9d6696804ec26aa12f8eed68b55c9b3c0fcf, SHA-256 53878789a42ed20ba0a911bbf42c65c61aa731342e681ff2a2200a02cb13e906.