Strong superconducting pairing strength and pseudogap features in a putative multiphase heavy-fermion superconductor CeRh 2 As 2 studied by soft point contact spectroscopy

作者：Qingxin Dong, Tong Shi, Pengtao Yang, Xin‐Yang Liu, Xiaofan Shi, Lei Wang, Junsen Xiang, Hanming Ma, Zhaoming Tian, Jianping Sun, Y. Uwatoko, Genfu Chen, Xinbo Wang, Jie Shen, Rui Wu, Xin Lu, Peijie Sun, Grzegorz Chajewski, D. Kaczorowski, Bosen Wang, Jinguang Cheng · 发表于：Physical review. B./Physical review. B · 年份：2025 · DOI：10.1103/physrevb.111.l180501 · 被引用次数：3 · 研究领域：Iron-based superconductors research、Rare-earth and actinide compounds、Physics of Superconductivity and Magnetism

${\mathrm{CeRh}}_{2}{\mathrm{As}}_{2}$ is a newly discovered candidate of multiphase heavy-fermion superconductor $({T}_{\mathrm{c}}\ensuremath{\approx}0.3 \mathrm{K})$ with intriguing physical properties. Here, we employ soft point-contact spectroscopy to investigate its energy gap behaviors in both the normal and superconducting states. The differential conductance below ${T}_{\mathrm{c}}$ reveals an estimated superconducting energy gap of $2{\mathrm{\ensuremath{\Delta}}}_{\mathrm{SC}}\ensuremath{\approx}0.24$ meV and thus an extremely strong superconducting pairing strength $2{\mathrm{\ensuremath{\Delta}}}_{\mathrm{SC}}/{k}_{\mathrm{B}}{T}_{\mathrm{c}}\ensuremath{\approx}8.8$, which is comparable to those of cuprates and iron-based high-${T}_{\mathrm{c}}$ superconductors as well as infinite-layer nickelates. Above ${T}_{\mathrm{c}}$, a well-defined pseudogap feature is manifested as a V-shaped dip in the differential conductance spanning an energy scale of $2{\mathrm{\ensuremath{\Delta}}}_{\mathrm{g}}\ensuremath{\approx}0.95\ensuremath{-}3.0$ meV. The pseudogap feature persists to the highest characteristic temperature of ${T}_{\mathrm{g}}\ensuremath{\approx}8\ensuremath{-}9$ K and is gradually suppressed by magnetic field of ${B}_{\mathrm{g}}\ensuremath{\approx}9.0\ifmmode\pm\else\textpm\fi{}0.5$ T regardless of its direction relative to the crystallographic axes. The observation of pseudogap features prior to the superconducting phase transition enriches the phase diagra...