A unique van Hove singularity in kagome superconductor CsV3-xTaxSb5 with enhanced superconductivity

Yang Luo, Yulei Han, Jinjin Liu, Hui Chen, Zihao Huang, Linwei Huai, Hongyu Li, Bingqian Wang, Jianchang Shen, Shuhan Ding, Zeyu Li, Shuting Peng, Zhiyuan Wei, Yu Miao, Xiupeng Sun, Zhipeng Ou, Ziji Xiang, Makoto Hashimoto, Donghui Lu, Yugui YaoHaitao Yang, Xianhui Chen, Hong Jun Gao*, Zhenhua Qiao*, Zhiwei Wang*, Junfeng He*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)

Abstract

Van Hove singularity (VHS) has been considered as a driving source for unconventional superconductivity. A VHS in two-dimensional (2D) materials consists of a saddle point connecting electron-like and hole-like bands. In a rare case, when a VHS appears at Fermi level, both electron-like and hole-like conduction can coexist, giving rise to an enhanced density of states as well as an attractive component of Coulomb interaction for unconventional electronic pairing. However, this van Hove scenario is often destroyed by an incorrect chemical potential or competing instabilities. Here, by using angle-resolved photoemission measurements, we report the observation of a VHS perfectly aligned with the Fermi level in a kagome superconductor CsV3-xTaxSb5 (x ~ 0.4), in which a record-high superconducting transition temperature is achieved among all the current variants of AV3Sb5 (A = Cs, Rb, K) at ambient pressure. Doping dependent measurements reveal the important role of van Hove scenario in boosting superconductivity, and spectroscopic-imaging scanning tunneling microscopy measurements indicate a distinct superconducting state in this system.

Original languageEnglish
Article number3819
JournalNature Communications
Volume14
Issue number1
DOIs
Publication statusPublished - Dec 2023

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