Electronic nature of chiral charge order in the kagome superconductor CsV₃Sb₅

Journal Article · 25 August 2021 · Physical Review B

DOI: https://doi.org/10.1103/physrevb.104.075148 · OSTI ID:1825254

Wang, Zhiwei  ^[1]; Jiang, Yu-Xiao ^[2]; Yin, Jia-Xin  ^[2]; Li, Yongkai ^[1]; Wang, Guan-Yong ^[3]; Huang, Hai-Li ^[3]; Shao, Sen ^[4]; Liu, Jinjin ^[1]; Zhu, Peng ^[1]; Shumiya, Nana ^[2]; Hossain, Md Shafayat ^[2]; Liu, Hongxiong ^[5]; Shi, Youguo ^[5]; Duan, Junxi  ^[1]; Li, Xiang ^[1]; Chang, Guoqing  ^[6]; Dai, Pengcheng ^[7]; Ye, Zijin ^[8]; Xu, Gang ^[8]; Wang, Yanchao ^[4] ; Zheng, Hao ^[3]; Jia, Jinfeng  ^[3]; Hasan, M. Zahid ^[9]; Yao, Yugui ^[1]

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1. Beijing Inst. of Technology (China)
2. Princeton Univ., NJ (United States)
3. Shanghai Jiao Tong Univ. (China)
4. Jilin Univ., Changchun (China)
5. Chinese Academy of Sciences (CAS), Beijing (China); Univ. of Chinese Academy of Sciences, Beijing (China)
6. Nanyang Technological Univ. (Singapore)
7. Rice Univ., Houston, TX (United States)
8. Huazhong Univ. of Science and Technology, Hubei (China)
9. Princeton Univ., NJ (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Quantum Science Center, Oak Ridge, TN (United States)

Kagome superconductors with T_C up to 7 K have been discovered for over 40 y. Recently, unconventional chiral charge order has been reported in kagome superconductor KV₃Sb₅, with an ordering temperature of one order of magnitude higher than the T_C. However, the chirality of the charge order has not been reported in the cousin kagome superconductor CsV₃Sb₅, and the electronic nature of the chirality remains elusive. In this paper, we report the observation of electronic chiral charge order in CsV₃Sb₅ via scanning tunneling microscopy (STM). We observe a 2 × 2 charge modulation and a 1 × 4 superlattice in both topographic data and tunneling spectroscopy. 2 × 2 charge modulation is highly anticipated as a charge order by fundamental kagome lattice models at van Hove filling, and is shown to exhibit intrinsic chirality. We find that the 1 × 4 superlattices form various small domain walls, and can be a surface effect as supported by our first-principles calculations. Crucially, we find that the amplitude of the energy gap opened by the charge order exhibits real-space modulations, and features 2 × 2 wave vectors with chirality, highlighting the electronic nature of the chiral charge order. STM study at 0.4 K reveals a superconducting energy gap with a gap size 2Δ = 0.85 meV, which estimates a moderate superconductivity coupling strength with 2Δ/k_BT_C = 3.9. Furthermore, when further applying a c-axis magnetic field, vortex core bound states are observed within this gap, indicative of clean-limit superconductivity.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: Gordon and Betty Moore Foundation; National Natural Science Foundation of China; Natural Science Foundation of China; USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: AC02-05CH11231; SC0012311
• OSTI ID: 1825254
• Journal Information: Physical Review B, Journal Name: Physical Review B Journal Issue: 7 Vol. 104; ISSN 2469-9950
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English