Nodeless electron pairing in CsV3Sb5-derived kagome superconductors

Autor: Yigui Zhong, Jinjin Liu, Xianxin Wu, Zurab Guguchia, J.-X. Yin, Akifumi Mine, Yongkai Li, Sahand Najafzadeh, Debarchan Das, Charles Mielke, Rustem Khasanov, Hubertus Luetkens, Takeshi Suzuki, Kecheng Liu, Xinloong Han, Takeshi Kondo, Jiangping Hu, Shik Shin, Zhiwei Wang, Xun Shi, Yugui Yao, Kozo Okazaki
Rok vydání: 2023
Předmět:
Zdroj: Nature. 617:488-492
ISSN: 1476-4687
0028-0836
DOI: 10.1038/s41586-023-05907-x
Popis: The newly discovered kagome superconductors represent a promising platform for investigating the interplay between band topology, electronic order, and lattice geometry. Despite extensive research efforts on this system, the nature of the superconducting ground state remains elusive. In particular, consensus on the electron pairing symmetry has not been achieved so far, in part owing to the lack of a momentum-resolved measurement of the superconducting gap structure. Here we report the direct observation of a nodeless, nearly isotropic, and orbital-independent superconducting gap in the momentum space of two exemplary CsV$_3$Sb$_5$-derived kagome superconductors -- Cs(V$_{0.93}$Nb$_{0.07}$)$_3$Sb$_5$ and Cs(V$_{0.86}$Ta$_{0.14}$)$_3$Sb$_5$, using ultrahigh resolution and low-temperature angle-resolved photoemission spectroscopy (ARPES). Remarkably, such a gap structure is robust to the appearance or absence of charge order in the normal state, tuned by isovalent Nb/Ta substitutions of V. Moreover, we observe a signature of the time-reversal symmetry (TRS) breaking inside the superconducting state, which extends the previous observation of TRS-breaking CDW in the kagome lattice. Our comprehensive characterizations of the superconducting state provide indispensable information on the electron pairing of kagome superconductors, and advance our understanding of unconventional superconductivity and intertwined electronic orders.
Databáze: OpenAIRE
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