发表机构
Max Planck Institute for Chemical Physics of Solids; Institute for Solid State and Materials Physics, Technische Universität Dresden; Dresden High Magnetic Field Laboratory (HLD-EMFL) and Würzburg-Dresden Cluster of Excellence ctd.qmat, Helmholtz-Zentrum Dresden-Rossendorf（马克斯·普朗克固体化学物理研究所; 德累斯顿工业大学固相与材料物理研究所; 德累斯顿强磁场实验室（HLD-EMFL）和维尔茨堡-德累斯顿卓越集群ctd.qmat，亥姆霍兹-德累斯顿-罗斯多夫中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
通过La替代单晶研究，发现CeRh2As2中晶格膨胀抑制近藤效应，且Tc和T0快速下降，表明相I具有巡游电子起源。
AI 中文摘要
CeRh$_2$As$_2$因其不寻常的两相超导电性而受到广泛关注。超导（SC）相出现在Ce-4$f$矩的有序态（相I）中，转变温度$T_{\mathrm{c}}$ = 0.35 K，该有序态在$T_{\mathrm{0}}$ = 0.55 K以下形成。相I的微观本质尚未完全确定。我们报道了在Ce$_{1-\textit{x}}$La$_\textit{x}$Rh$_2$As$_2$（$x$ 最高至0.1）中La替代对这些低温相影响的单晶研究。晶格参数随$x$单调增加，对应于$x$ = 0.1时约-0.3 GPa的有效负压力。虽然Ce$^{3+}$局域价态和非费米液体行为得以保持，但原始样品中约45 K的电阻率相干峰$T^{*}_{\mathrm{max}}$随$x$增加而向更低温度移动，表明晶格膨胀抑制了近藤能量尺度。另一方面，当$x$ > 0.05时，$T_{\mathrm{c}}$和$T_{\mathrm{0}}$均被迅速抑制至0.1 K以下。值得注意的是，在中等负压力下$T_{\mathrm{c}}$如此迅速的下降出乎意料，但更符合替代引起的无序效应，该效应在非常规超导体中导致强对破。观察到的相I在压力和无序下的脆弱性可能暗示其巡游电子起源。
英文摘要
CeRh$_2$As$_2$ has been receiving considerable attention due to its unusual two-phase superconductivity. The superconducting (SC) phase appears at $T_{\mathrm{c}}$ = 0.35 K in an ordered state (phase I) of the Ce-4$f$ moments, which develops below $T_{\mathrm{0}}$ = 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$_{1-\textit{x}}$La$_\textit{x}$Rh$_2$As$_2$ 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 $T^{*}_{\mathrm{max}}$ $\approx$ 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 $T_{\mathrm{c}}$ and $T_{\mathrm{0}}$ are rapidly suppressed to below 0.1 K for $x$ $>$ 0.05. Notably, such a rapid decrease of $T_{\mathrm{c}}$ 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.
Journal refPhys. Rev. B 114, 115129 (2026)
