La substitution studies on the heavy-fermion superconductor CeRh2As2
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 T*max ≈ 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 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.
Versions
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BibTeX
@misc{sankar2026substitution,
title = {{La substitution studies on the heavy-fermion superconductor CeRh$_2$As$_2$}},
author = {Sushma Lakshmi Ravi Sankar and Manuel Brando and Jochen Wosnitza and Seunghyun Khim},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.17080},
eprint = {2609.17080},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.17080},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - La substitution studies on the heavy-fermion superconductor CeRh_2As_2
AU - Sushma Lakshmi Ravi Sankar
AU - Manuel Brando
AU - Jochen Wosnitza
AU - Seunghyun Khim
PY - 2026
DA - 2026/09/15
PB - arXiv
DO - 10.48550/arxiv.2609.17080
UR - https://arxiv.org/abs/2609.17080
AB - CeRh_2As_2 has been receiving considerable attention due to its unusual two-phase superconductivity. The superconducting (SC) phase appears at T_c = 0.35 K in an ordered state (phase I) of the Ce-4f moments, which develops below T_0 = 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 Ce_1−xLa_xRh_2As_2 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 Ce^3+ local valence state and the non-Fermi-liquid behavior are preserved, the resistivity coherence maximum T^*_max ≈ 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 T_c and T_0 are rapidly suppressed to below 0.1 K for x > 0.05. Notably, such a rapid decrease of T_c under moderate negative pressure is unexpected, but is rather consistent with 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.
ER -