pith. sign in

arxiv: 1906.08478 · v1 · pith:6B5ZIVB2new · submitted 2019-06-20 · ❄️ cond-mat.supr-con · cond-mat.mtrl-sci

Electrodynamic response of Ba(Fe1-xRhx)2As2 across the s+- to s++ order parameter transition

D. Torsello , R. Gerbaldo , L. Gozzelino , M. A. Tanatar , R. Prozorov , P. C. Canfield , G. Ghigo This is my paper

Pith reviewed 2026-05-25 19:36 UTC · model grok-4.3

classification ❄️ cond-mat.supr-con cond-mat.mtrl-sci
keywords Ba(Fe1-xRhx)2As2iron-based superconductorss+- to s++ transitionorder parameter symmetrysurface resistancenormal conductivitydisorder effectselectrodynamic response
0
0 comments X

The pith

Peculiarities in surface resistance and normal conductivity mark the s+- to s++ order parameter transition in Ba(Fe1-xRhx)2As2.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper examines the microwave response of the iron-based superconductor Ba(Fe1-xRhx)2As2 as rhodium doping increases disorder. Earlier measurements of critical temperature and penetration depth indicated that the superconducting order parameter symmetry switches from s+- to s++ at a certain doping level. The new analysis finds distinct anomalies in surface resistance and the conductivity of normal electrons that appear at the same doping values. These anomalies supply an independent signature of the symmetry change. A sympathetic reader would care because multiple independent observables now line up at the transition point, making the disorder-driven switch in pairing symmetry more firmly established.

Core claim

In the same samples where the s+- to s++ transition had been inferred from critical temperature and London penetration depth, the electrodynamic response shows peculiarities in the behaviour of the surface resistance and normal conductivity that can be considered traces of the transition itself.

What carries the argument

the doping-dependent surface resistance and normal conductivity, whose temperature profiles exhibit features that coincide with the previously identified symmetry transition point

If this is right

  • The s+- to s++ symmetry change produces measurable changes in the microwave surface resistance.
  • Normal conductivity displays distinct temperature dependence across the transition doping level.
  • These electrodynamic features occur at the same doping where earlier Tc and penetration depth results already signaled the transition.
  • Surface resistance and conductivity measurements can serve as additional probes for the order parameter symmetry switch.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • If the anomalies prove robust, microwave measurements could provide a practical way to locate the transition without needing penetration depth data.
  • The result raises the possibility that similar symmetry switches in other iron-based compounds might be located by searching for matching resistance features.
  • Disorder could be used deliberately to tune both the pairing symmetry and the electromagnetic response in this family of materials.

Load-bearing premise

The observed peculiarities in surface resistance and normal conductivity arise specifically from the s+- to s++ transition rather than from unrelated disorder effects or measurement artifacts.

What would settle it

If the same peculiarities fail to appear precisely at the rhodium concentration where Tc and penetration depth data indicate the transition, or if identical features appear in samples that remain in the s+- state.

Figures

Figures reproduced from arXiv: 1906.08478 by D. Torsello, G. Ghigo, L. Gozzelino, M. A. Tanatar, P. C. Canfield, R. Gerbaldo, R. Prozorov.

Figure 1
Figure 1. Figure 1: Normalized quasiparticle conductivity vs temperature curves for increasing levels of disorder (d.p.a.). The s± to s++ transition takes place between d.p.a. = 4.10×10−3 and 5.12×10−3 , and is indicated by the green arrow [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: a) Normalized surface resistance (Rs) and b) reactance (Xs) vs temperature curves for increasing levels of disorder (d.p.a.). The s± to s++ transition takes place between d.p.a. = 4.10×10−3 and 5.12×10−3 , and is indicated by the green arrows. The surface impedance Zs = Rs + iXs as a function of temperature is shown in [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗
read the original abstract

Most iron-based superconductors are characterized by the s+- symmetry of their order parameter, and are expected to go through a transition to the s++ state if enough disorder is introduced. We previously reported the observation of this transition in Ba(Fe1-xRhx)2As2 through a study of the disorder dependence of the critical temperature and low-temperature London penetration depth. In this paper we report on the analysis of the electrodynamic response of the same sample across the transition and we identify peculiarities in the behaviour of the surface resistance and normal conductivity, that can be considered as traces of the transition itself.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

0 major / 2 minor

Summary. The manuscript analyzes the electrodynamic response (surface resistance and normal conductivity) of Ba(Fe1-xRhx)2As2 crystals across the doping range where a disorder-driven s+- to s++ order-parameter transition was previously identified from Tc(x) and low-T London penetration depth on the same samples. The authors report qualitative peculiarities in these quantities and interpret them as traces of the symmetry transition.

Significance. If the reported features prove robust under quantitative scrutiny, the work supplies additional experimental signatures for the s+-/s++ crossover in iron-based superconductors, complementing the Tc and λ probes already published on identical crystals. The same-sample approach is a clear strength, as it minimizes sample-to-sample variation and allows direct correlation of multiple observables. The authors correctly frame the new features as suggestive rather than as an independent proof of the transition.

minor comments (2)
  1. [Discussion] The discussion of possible alternative explanations (disorder effects unrelated to symmetry change or experimental artifacts) is acknowledged but remains qualitative; a short paragraph bounding their expected size relative to the observed peculiarities would improve clarity.
  2. [Figures] Ensure all plots of Rs and σn include explicit error bars or uncertainty estimates derived from the raw data reduction procedure.

Simulated Author's Rebuttal

0 responses · 0 unresolved

We thank the referee for the positive assessment of our work and the recommendation for minor revision. The same-sample approach and framing of the features as suggestive are indeed strengths of the manuscript. No major comments were enumerated in the report, so we provide no point-by-point responses below.

Circularity Check

0 steps flagged

No significant circularity

full rationale

The paper reports new measurements of surface resistance and normal conductivity on the same crystals previously characterized for the s+- to s++ transition via Tc(x) and λ(T,x). The identified peculiarities are presented as observational correlations with the prior transition location rather than any quantitative derivation or prediction that reduces to the input data by construction. The self-reference to earlier work on the same samples is used only to specify the doping range of interest and does not define or force the new electrodynamic features. No ansatz, fitted parameter, or uniqueness theorem is smuggled in; the central claim retains independent experimental content and is framed as suggestive.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Abstract-only review supplies no explicit free parameters, axioms, or invented entities; the central claim rests on the unstated assumption that the previously reported transition location is accurate and that the new features are causally linked to it.

pith-pipeline@v0.9.0 · 5673 in / 1097 out tokens · 18275 ms · 2026-05-25T19:36:06.181046+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Reference graph

Works this paper leans on

19 extracted references · 19 canonical work pages

  1. [1]

    A. V. Chubukov, D. V. Efremov, I. Eremin, Phys. Rev. B 78, 134512 (2008)

    work page 2008

  2. [2]

    Stanev, J

    V. Stanev, J. Kang, Z. Tesanovic, Phys. Rev. B 78, 184509 (2008)

    work page 2008

  3. [3]

    I. I. Mazin, D. J. Singh, M. D. Johannes, M. H. Du, Phys. Rev. Lett. 101, 057003 (2008)

    work page 2008

  4. [4]

    D. V. Efremov, M. M. Korshunov, O. V. Dolgov, A. A. Golubov, P. J. Hirschfeld, Phys. Rev. B 84, 180512(R) (2011)

    work page 2011

  5. [5]

    Y. Wang, A. Kreisel, P. J. Hirschfeld, V. Mishra, Phys. Rev. B 87, 094504 (2013)

    work page 2013

  6. [6]

    M. B. Schilling, A. Baumgartner, B. Gorshunov, E. S. Zhukova, V. A. Dravin, K. V. Mitsen, D. V. Efremov, O. V. Dolgov, K. Iida, M. Dressel, S. Zapf, Phys. Rev. B 93, 174515 (2016)

    work page 2016

  7. [7]

    Ghigo, D

    G. Ghigo, D. Torsello, G. A. Ummarino, L. Gozzelino, M. A. Tanatar, R. Prozorov, P. C. Canfield, Phys. Rev. Lett. 121, 107001 (2018)

    work page 2018

  8. [8]

    Ghigo, R

    G. Ghigo, R. Gerbaldo, L. Gozzelino, F. Laviano, T. Tamegai, IEEE Trans. Appl. Super- cond. 26, 1 (2016)

    work page 2016

  9. [9]

    N. Ni, M. E. Tillman, J.-Q. Yan, A. Kracher, S. T. Hannahs, S. L. Bud’ko, P. C. Canfield, Phys. Rev. B 78, 214515 (2008)

    work page 2008

  10. [10]

    N. Ni, A. Thaler, A. Kracher, J. Q. Yan, S. L. Bud’ko, P. C. Canfield, Phys. Rev. B 80, 024511 (2009)

    work page 2009

  11. [11]

    Hodovanets, A

    H. Hodovanets, A. Thaler, E. Mun, N. Ni, S. L. Bud’ko, P. C. Canfield, Philos. Mag. 93:6, 661-672 (2012)

    work page 2012

  12. [12]

    T. Sato, K. Niita, N. Matsuda, S. Hashimoto, Y. Iwamoto, S. Noda, T. Ogawa, H. Iwase, H. Nakashima, T. Fukahori, K. Okumura, T. Kai, S. Chiba, T. Furuta, L. Sihver, J. Nucl. Sci. Technol. 50, 913 (2013)

    work page 2013

  13. [13]

    J. F. Ziegler, M. Ziegler, J. Biersack, Nucl. Instrum. Meth. B 268, 1818 (2010)

    work page 2010

  14. [14]

    Ghigo, G

    G. Ghigo, G. A. Ummarino, L. Gozzelino, T. Tamegai, Phys. Rev. B 96, 014501 (2017)

    work page 2017

  15. [15]

    Ghigo, G

    G. Ghigo, G. A. Ummarino, L. Gozzelino, R. Gerbaldo, F. Laviano, D. Torsello, T. Tamegai, Sci. Rep. 7, 13029 (2017)

    work page 2017

  16. [16]

    Ghigo, D

    G. Ghigo, D. Torsello, R. Gerbaldo, L. Gozzelino, F. Laviano, T. Tamegai, Supercond. Sci. Technol. 31, 034006 (2018)

    work page 2018

  17. [17]

    Barannik, N

    A. Barannik, N. T. Cherpak, M. A. Tanatar, S. Vitusevich, V. Skresanov, P. C. Canfield, R. Prozorov, Phys. Rev. B 87, 014506 (2013)

    work page 2013

  18. [18]

    Takahashi, Y

    H. Takahashi, Y. Imai, S. Komiya, I. Tsukada, A. Maeda, Phys. Rev. B 84, 132503 (2011)

    work page 2011

  19. [19]

    A. H. Panaretos, D. H. Werner, Antennas and Propagation (APSURSI), 2016 IEEE International Symposium, 553 (2016)

    work page 2016