Evidence of a strongly anisotropic superconducting gap in kagome superconductor CsV3Sb5: A study of directional point-contact Andreev reflection spectroscopy

doi:10.1088/1674-1056/ae27b0

中国物理B ›› 2026, Vol. 35 ›› Issue (5): 57405-057405.doi: 10.1088/1674-1056/ae27b0

Evidence of a strongly anisotropic superconducting gap in kagome superconductor CsV₃Sb₅: A study of directional point-contact Andreev reflection spectroscopy

Yu-Qing Zhao(赵宇清)^1,†, Zhi-Fan Wu(武治帆)^1,†, Hai-Yan Zuo(左海艳)¹, Wei-Ming Lao(劳威铭)¹, Wang-Ju Yang(杨王菊)¹, Qiu-Xia Chen(陈秋霞)¹, Yao He(何垚)¹, Hai Wang(王海)¹, Wenxin Lv(吕文欣)^2,3, Qi Wang(王琦)⁴, Yan-Peng Qi(齐彦鹏)⁴, Gang Mu(牟刚)⁵, Hechang Lei(雷和畅)^2,3,‡, and Cong Ren(任聪)^1,§

1 School of Physics and Astronomy, Yunnan University, Kunming 650500, China;
2 School of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials and Micro-nano Devices, Renmin University of China, Beijing 100872, China;
3 Key Laboratory of Quantum State Construction and Manipulation (Ministry of Education), Renming University of China, Bijing 100872, China;
4 State Key Laboratory of Quantum Functional Materials, School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China;
5 State Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China

收稿日期:2025-09-17 修回日期:2025-12-01 接受日期:2025-12-04 出版日期:2026-04-24 发布日期:2026-05-15
通讯作者: Hechang Lei, Cong Ren E-mail:hlei@ruc.edu.cn;cren@ynu.edu.cn
基金资助:
C.R. acknowledges financial support from the National Natural Science Foundation of China and the Joint Fund of Yunnan Provincial Science and Technology Department (Grant No. 2019FY003008). H. Wang acknowledges financial support from the National Natural Science Foundation of China (Grant No. 62164006) and Yunnan Fundamental Reseach Projects (Grant No. 202201AS07008). Y. Q. Zhao and Z. F. Wu are thankful for financial support from the “16th Graduate Research Innovation Project” of Yunnan University (Grant No. KC-24249857). H.C.L. was supported by the National Key R&D Program of China (Grant No. 2022YFA1403800) and the National Natural Science Foundation of China (Grant No. 12274459). Y.Q. was supported by the National Key R&D Program of China (Grant No. 2018YFA0704300).

Evidence of a strongly anisotropic superconducting gap in kagome superconductor CsV₃Sb₅: A study of directional point-contact Andreev reflection spectroscopy

1 School of Physics and Astronomy, Yunnan University, Kunming 650500, China;
2 School of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials and Micro-nano Devices, Renmin University of China, Beijing 100872, China;
3 Key Laboratory of Quantum State Construction and Manipulation (Ministry of Education), Renming University of China, Bijing 100872, China;
4 State Key Laboratory of Quantum Functional Materials, School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China;
5 State Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China

Received:2025-09-17 Revised:2025-12-01 Accepted:2025-12-04 Online:2026-04-24 Published:2026-05-15
Contact: Hechang Lei, Cong Ren E-mail:hlei@ruc.edu.cn;cren@ynu.edu.cn
Supported by:
C.R. acknowledges financial support from the National Natural Science Foundation of China and the Joint Fund of Yunnan Provincial Science and Technology Department (Grant No. 2019FY003008). H. Wang acknowledges financial support from the National Natural Science Foundation of China (Grant No. 62164006) and Yunnan Fundamental Reseach Projects (Grant No. 202201AS07008). Y. Q. Zhao and Z. F. Wu are thankful for financial support from the “16th Graduate Research Innovation Project” of Yunnan University (Grant No. KC-24249857). H.C.L. was supported by the National Key R&D Program of China (Grant No. 2022YFA1403800) and the National Natural Science Foundation of China (Grant No. 12274459). Y.Q. was supported by the National Key R&D Program of China (Grant No. 2018YFA0704300).

摘要/Abstract

摘要： In the recently discovered V-based kagome superconductors $A$V$_3$Sb$_5$ ($A = {\rm K}$, Rb, Cs), superconductivity intertwines with an unconventional charge density wave (CDW), raising fundamental questions concerning the superconducting gap structure in the presence of such intertwined orders. Here, we perform the first directional point-contact Andreev reflection (PCAR) spectroscopy measurement on CsV$_3$Sb$_5$ to probe its superconducting gap structure. Strikingly distinct PCAR spectra emerge depending on the current injection direction: an in-gap zero-bias conductance peak dominates for currents parallel to the $ab$-plane, contrasting to a gap-like structure observed perpendicularly. Quantitative analysis using a modified BTK-model estimates a pronounced gap anisotropy of $\sim$70 % with a gap minimum $\sim 0.15$ meV. These results provide a foundation for further understanding the nature of the topological superconducting state on the sample edges.

关键词: kagome superconductor, gap symmetry, Andreev reflection spectroscopy

Abstract: In the recently discovered V-based kagome superconductors $A$V$_3$Sb$_5$ ($A = {\rm K}$, Rb, Cs), superconductivity intertwines with an unconventional charge density wave (CDW), raising fundamental questions concerning the superconducting gap structure in the presence of such intertwined orders. Here, we perform the first directional point-contact Andreev reflection (PCAR) spectroscopy measurement on CsV$_3$Sb$_5$ to probe its superconducting gap structure. Strikingly distinct PCAR spectra emerge depending on the current injection direction: an in-gap zero-bias conductance peak dominates for currents parallel to the $ab$-plane, contrasting to a gap-like structure observed perpendicularly. Quantitative analysis using a modified BTK-model estimates a pronounced gap anisotropy of $\sim$70 % with a gap minimum $\sim 0.15$ meV. These results provide a foundation for further understanding the nature of the topological superconducting state on the sample edges.

Key words: kagome superconductor, gap symmetry, Andreev reflection spectroscopy

中图分类号: (Superconducting materials other than cuprates)

74.70.-b

74.20.Rp (Pairing symmetries (other than s-wave)) 74.45.+c (Proximity effects; Andreev reflection; SN and SNS junctions)

Yu-Qing Zhao(赵宇清), Zhi-Fan Wu(武治帆), Hai-Yan Zuo(左海艳), Wei-Ming Lao(劳威铭), Wang-Ju Yang(杨王菊), Qiu-Xia Chen(陈秋霞), Yao He(何垚), Hai Wang(王海), Wenxin Lv(吕文欣), Qi Wang(王琦), Yan-Peng Qi(齐彦鹏), Gang Mu(牟刚), Hechang Lei(雷和畅), and Cong Ren(任聪). Evidence of a strongly anisotropic superconducting gap in kagome superconductor CsV₃Sb₅: A study of directional point-contact Andreev reflection spectroscopy[J]. 中国物理B, 2026, 35(5): 57405-057405.

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Evidence of a strongly anisotropic superconducting gap in kagome superconductor CsV₃Sb₅: A study of directional point-contact Andreev reflection spectroscopy

Evidence of a strongly anisotropic superconducting gap in kagome superconductor CsV₃Sb₅: A study of directional point-contact Andreev reflection spectroscopy

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