Charge-density-wave-driven electronic nematicity in a kagome superconductor

• Published in: Nature (London) 2022-04, Vol.604 (7904), p.59-64
• Main Authors: Nie, Linpeng, Sun, Kuanglv, Ma, Wanru, Song, Dianwu, Zheng, Lixuan, Liang, Zuowei, Wu, Ping, Yu, Fanghang, Li, Jian, Shan, Min, Zhao, Dan, Li, Shunjiao, Kang, Baolei, Wu, Zhimian, Zhou, Yanbing, Liu, Kai, Xiang, Ziji, Ying, Jianjun, Wang, Zhenyu, Wu, Tao, Chen, Xianhui
• Format: Article
• Language: English
• Subjects: 140/131; 639/766/119/1003; 639/766/119/995; Anisotropy; Charge density waves; Energy; High temperature; High temperature superconductors; Humanities and Social Sciences; Magnetic resonance; multidisciplinary; NMR; Nuclear magnetic resonance; Scanning tunneling microscopy; Science; Science (multidisciplinary); Spectroscopy; Spectrum analysis; Superconductivity; Symmetry; Temperature dependence; Topography; Transition temperature; Transition temperatures; Unconventional superconductors; Vanadium
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/s41586-022-04493-8

Electronic nematicity, in which rotational symmetry is spontaneously broken by electronic degrees of freedom, has been demonstrated as a ubiquitous phenomenon in correlated quantum fluids including high-temperature superconductors and quantum Hall systems 1 , 2 . Notably, the electronic nematicity in high-temperature superconductors exhibits an intriguing entanglement with superconductivity, generating complicated superconducting pairing and intertwined electronic orders. Recently, an unusual competition between superconductivity and a charge-density-wave (CDW) order has been found in the A V 3 Sb 5 ( A  = K, Rb, Cs) family with two-dimensional vanadium kagome nets 3 – 8 . Whether these phenomena involve electronic nematicity is still unknown. Here we report evidence for the existence of electronic nematicity in CsV 3 Sb 5 , using a combination of elastoresistance measurements, nuclear magnetic resonance (NMR) and scanning tunnelling microscopy/spectroscopy (STM/S). The temperature-dependent elastoresistance coefficient ( m 11 minus m 12 ) and NMR spectra demonstrate that, besides a C 2 structural distortion of the 2 a 0  × 2 a 0 supercell owing to out-of-plane modulation, considerable nematic fluctuations emerge immediately below the CDW transition (approximately 94 kelvin) and finally a nematic transition occurs below about 35 kelvin. The STM experiment directly visualizes the C 2 -structure-pinned long-range nematic order below the nematic transition temperature, suggesting a novel nematicity described by a three-state Potts model. Our findings indicate an intrinsic electronic nematicity in the normal state of CsV 3 Sb 5 , which sets a new paradigm for revealing the role of electronic nematicity on pairing mechanism in unconventional superconductors. Charge-density-wave-driven electronic nematicity that occurs well below the charge-density-wave transition temperature is reported in the kagome superconductor CsV 3 Sb 5 .