Nodeless electron pairing in CsV3Sb5-derived kagome superconductors

Yigui Zhong; Jinjin Liu; Xianxin Wu; Zurab Guguchia; J-X Yin; Akifumi Mine; Yongkai Li; Sahand Najafzadeh; Debarchan Das; Charles Mielke 3rd; Rustem Khasanov; Hubertus Luetkens; Takeshi Suzuki; Kecheng Liu; Xinloong Han; Takeshi Kondo; Jiangping Hu; Shik Shin; Zhiwei Wang; Xun Shi; Yugui Yao; Kozo Okazaki

doi:10.1038/s41586-023-05907-x

Nodeless electron pairing in CsV₃Sb₅-derived kagome superconductors

Nature. 2023 May;617(7961):488-492. doi: 10.1038/s41586-023-05907-x. Epub 2023 Apr 26.

Authors

Yigui Zhong^#¹, Jinjin Liu^#^{2

3}, Xianxin Wu^#⁴, Zurab Guguchia⁵, J-X Yin^{6

7}, Akifumi Mine¹, Yongkai Li^{2

3

8}, Sahand Najafzadeh¹, Debarchan Das⁵, Charles Mielke 3rd⁵, Rustem Khasanov⁵, Hubertus Luetkens⁵, Takeshi Suzuki¹, Kecheng Liu¹, Xinloong Han⁹, Takeshi Kondo^{1

10}, Jiangping Hu¹¹, Shik Shin^{1

12}, Zhiwei Wang^{13

14

15}, Xun Shi^{16

17}, Yugui Yao^{2

3

8}, Kozo Okazaki^{18

19

20}

Affiliations

¹ Institute for Solid States Physics, The University of Tokyo, Kashiwa, Japan.
² Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing, China.
³ Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems, Beijing Institute of Technology, Beijing, China.
⁴ CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing, China.
⁵ Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, Villigen PSI, Switzerland.
⁶ Laboratory for Quantum Emergence, Department of Physics, Southern University of Science and Technology, Shenzhen, China.
⁷ Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area (Guangdong), Shenzhen, China.
⁸ Material Science Center, Yangtze Delta Region Academy of Beijing Institute of Technology, Jiaxing, China.
⁹ Kavli Institute of Theoretical Sciences, University of Chinese Academy of Sciences, Beijing, China.
¹⁰ Trans-scale Quantum Science Institute, The University of Tokyo, Tokyo, Japan.
¹¹ Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, China.
¹² Office of University Professor, The University of Tokyo, Kashiwa, Japan.
¹³ Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing, China. [email protected].
¹⁴ Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems, Beijing Institute of Technology, Beijing, China. [email protected].
¹⁵ Material Science Center, Yangtze Delta Region Academy of Beijing Institute of Technology, Jiaxing, China. [email protected].
¹⁶ Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing, China. [email protected].
¹⁷ Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems, Beijing Institute of Technology, Beijing, China. [email protected].
¹⁸ Institute for Solid States Physics, The University of Tokyo, Kashiwa, Japan. [email protected].
¹⁹ Trans-scale Quantum Science Institute, The University of Tokyo, Tokyo, Japan. [email protected].
²⁰ Material Innovation Research Center, The University of Tokyo, Kashiwa, Japan. [email protected].

^# Contributed equally.

PMID: 37100906
DOI: 10.1038/s41586-023-05907-x

Abstract

The newly discovered kagome superconductors represent a promising platform for investigating the interplay between band topology, electronic order and lattice geometry^1-9. Despite extensive research efforts on this system, the nature of the superconducting ground state remains elusive^10-17. In particular, consensus on the electron pairing symmetry has not been achieved so far^18-20, 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 CsV₃Sb₅-derived kagome superconductors-Cs(V_0.93Nb_0.07)₃Sb₅ and Cs(V_0.86Ta_0.14)₃Sb₅-using ultrahigh-resolution and low-temperature angle-resolved photoemission spectroscopy. 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. Our comprehensive characterizations of the superconducting gap provide indispensable information on the electron pairing symmetry of kagome superconductors, and advance our understanding of the superconductivity and intertwined electronic orders in quantum materials.

Publication types

Research Support, Non-U.S. Gov't