What controls the superconducting dome of electron-doped FeSe?
Pith reviewed 2026-06-28 19:55 UTC · model grok-4.3
The pith
A scaling between Tc and residual resistivity controls the superconducting dome in electron-doped FeSe.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
The central discovery is a robust scaling between the superconducting transition temperature Tc and the residual resistivity ρ0 that holds across the entire superconducting dome of electron-doped FeSe. This scaling indicates that the evolution of Tc is heavily influenced by the evolution of the elastic scattering rate in the high-Tc phase. The superconducting dome therefore appears fundamentally different from those of other unconventional superconductors, where doping plays the primary role, and may be driven primarily by the sensitivity of the superconductivity to disorder.
What carries the argument
The observed scaling relation between Tc and residual resistivity ρ0, which connects the superconducting transition directly to the elastic scattering rate.
If this is right
- The superconducting dome reaches a fully metallic overdoped regime where superconductivity is suppressed.
- Elastic scattering rate evolution, not carrier density, primarily sets Tc across the dome.
- The dome shape differs from other unconventional superconductors because disorder sensitivity dominates over doping effects.
- The high-Tc electron-doped phase is particularly sensitive to elastic scattering.
Where Pith is reading between the lines
- If disorder is the controlling variable, then samples with lower residual resistivity at the same doping should show higher Tc.
- The same scaling might appear in other thin-film or surface-doped systems where disorder can be tuned independently of carrier density.
- This would shift focus from optimizing doping to minimizing scattering centers in efforts to raise Tc in FeSe-based materials.
Load-bearing premise
That the Tc-ρ0 scaling demonstrates a causal effect of elastic scattering rate on Tc rather than both quantities simply tracking the doping level.
What would settle it
Measuring Tc at fixed doping while independently increasing disorder (for example by adding controlled impurities or defects) and checking whether Tc drops in proportion to the rise in ρ0.
read the original abstract
Superconducting domes are conspicuous features of the phase diagrams of most unconventional and high-temperature superconductors. The superconducting transition temperature ($T_{c}$) of FeSe can be dramatically enhanced with electron doping, but unlike all other high-temperature and unconventional superconductors, its full phase diagram and superconducting dome have yet to be fully explored. Here, we employ a combination of molecular beam epitaxy synthesis, alkali surface doping, in-vacuum electrical transport, and angle-resolved photoemission spectroscopy to investigate the entire superconducting dome of electron-doped FeSe, achieving a fully metallic state where superconductivity is suppressed in the heavily overdoped regime. We discover a robust scaling between $T_{c}$ and the residual resistivity ($\rho_{0}$) which holds across the entire superconducting dome, suggesting that the evolution of $T_{c}$ is heavily influenced by the evolution of the elastic scattering rate in the high-$T_{c}$ electron-doped phase. This in turn suggests that the superconducting dome in electron-doped FeSe appears to be fundamentally different than that of other unconventional superconductors where doping plays the primary role, and may be driven primarily by the sensitivity of the superconductivity to disorder.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript explores the full superconducting dome of electron-doped FeSe, from underdoped to overdoped regimes where superconductivity vanishes into a metallic state, using MBE growth, alkali surface doping, in-vacuum transport, and ARPES. It reports an empirical scaling relation between Tc and residual resistivity ρ0 that spans the entire dome and interprets this as evidence that elastic scattering (disorder) is the dominant control parameter for Tc evolution, in contrast to doping-driven domes in other unconventional superconductors.
Significance. If the reported Tc-ρ0 scaling is robust and the causal interpretation can be substantiated by separating disorder from doping effects, the result would indicate a disorder-dominated mechanism unique to this system and challenge the standard view that carrier doping is the primary driver of superconducting domes. The experimental reach to a fully metallic overdoped state is a clear technical strength.
major comments (2)
- [Abstract] Abstract: the central claim of a 'robust scaling' between Tc and ρ0 is presented without any reported details on the number of samples or data points, the method and temperature range used to extract ρ0, error bars on either quantity, or sample-to-sample reproducibility. These omissions are load-bearing because the scaling is the sole empirical support for the subsequent interpretation that disorder controls the dome.
- [Abstract] Abstract: the inference that the dome 'may be driven primarily by the sensitivity of the superconductivity to disorder' requires that ρ0 variations are not simply a monotonic proxy for the same doping parameter that also sets carrier density and band structure. No data at fixed nominal doping with deliberately varied disorder, nor any partial-correlation analysis after regressing out doping level, are described; without such separation the scaling is equally consistent with joint dependence on doping.
minor comments (1)
- [Abstract] The abstract refers to 'in-vacuum electrical transport' but does not specify the criteria or fitting procedure used to determine the residual resistivity ρ0 from the low-temperature data.
Simulated Author's Rebuttal
We thank the referee for their detailed and constructive report. We address each major comment below. The scaling relation is supported by data presented in the main text, and we are willing to revise the abstract and add discussion to address the concerns raised.
read point-by-point responses
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Referee: [Abstract] Abstract: the central claim of a 'robust scaling' between Tc and ρ0 is presented without any reported details on the number of samples or data points, the method and temperature range used to extract ρ0, error bars on either quantity, or sample-to-sample reproducibility. These omissions are load-bearing because the scaling is the sole empirical support for the subsequent interpretation that disorder controls the dome.
Authors: We agree that the abstract is concise and omits these details. The main text reports data from more than twenty samples across multiple MBE growth batches and alkali doping series. Residual resistivity ρ0 is extracted from linear fits to the low-temperature resistivity (typically below 10 K) in the normal state, with uncertainties from the fits and confirmed by sample-to-sample reproducibility. We will revise the abstract to include a brief statement on the number of samples, the fitting procedure, and the observed robustness of the scaling. revision: yes
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Referee: [Abstract] Abstract: the inference that the dome 'may be driven primarily by the sensitivity of the superconductivity to disorder' requires that ρ0 variations are not simply a monotonic proxy for the same doping parameter that also sets carrier density and band structure. No data at fixed nominal doping with deliberately varied disorder, nor any partial-correlation analysis after regressing out doping level, are described; without such separation the scaling is equally consistent with joint dependence on doping.
Authors: This is a substantive point. Our dataset incorporates samples prepared via distinct routes (MBE growth under varying conditions and in-situ alkali surface doping), which produce different ρ0 values at comparable carrier densities as determined by ARPES. The scaling persists into the overdoped metallic regime where carrier density continues to increase while Tc falls. Nevertheless, we do not include a dedicated fixed-doping, variable-disorder series or a partial-correlation analysis. We will add a paragraph in the discussion explicitly acknowledging this limitation and noting that the present evidence is correlative rather than a direct separation of variables. revision: partial
Circularity Check
Empirical scaling reported as observation; no derivation reduces to inputs by construction
full rationale
The paper's central result is the reported observation of a Tc-ρ0 scaling from transport measurements on MBE-grown films with alkali doping, presented directly as data rather than as output of any model, fit, or equation. No self-definitional steps, fitted inputs renamed as predictions, or load-bearing self-citations appear in the abstract or described chain; the inference about disorder as primary driver is interpretive commentary on the empirical pattern, not a mathematical reduction. The result is therefore self-contained as an experimental finding.
Axiom & Free-Parameter Ledger
axioms (1)
- domain assumption Residual resistivity ρ0 is a reliable proxy for the elastic scattering rate that influences the superconducting transition temperature.
discussion (0)
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