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La substitution studies on the heavy-fermion superconductor CeRh2As2

Sushma Lakshmi Ravi Sankar1,2, Manuel Brando1, Jochen Wosnitza2,3, and Seunghyun Khim1,*

  • *Contact author: seunghyun.khim@cpfs.mpg.de
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Phys. Rev. B 114, 115129 – Published 25 August, 2026

DOI: https://doi.org/10.1103/f79y-ssdx

Abstract

CeRh2As2 has been receiving considerable attention due to its unusual two-phase superconductivity. The superconducting (SC) phase appears at Tc=0.35 K in an ordered state (phase I) of the Ce−4f moments, which develops below T0=0.55 K. The microscopic nature of phase I has not been fully established yet. We report a single-crystal study of the effect of La substitution on these low-temperature phases in Ce1−xLaxRh2As2 up to x=0.1. The lattice parameters increase monotonically with x, corresponding to an effective negative pressure of approximately −0.3 GPa for x=0.1. While the Ce3+ local valence state and the non-Fermi-liquid behavior are preserved, the resistivity coherence maximum Tmax*≈45 K in the pristine sample shifts to lower temperatures with increasing x, indicating a suppression of the Kondo energy scale upon lattice expansion. On the other hand, both Tc and T0 are rapidly suppressed to below 0.1 K for x>0.05. Notably, such a rapid decrease of Tc under moderate negative pressure is unexpected, but is rather consistent with a substitution-induced disorder effect which leads to strong pair breaking in unconventional superconductors. The observed fragility of phase I under both pressure and disorder may imply its itinerant origin.

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Phys. Rev. B 114, 115129– Published 25 August, 2026
  • Received 23 February 2026
  • Revised 5 August 2026
  • Accepted 7 August 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Open access publication funded by Max Planck Society.

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