Polar surface and interface play a pivotal role for realizing exotic properties of materials, and a search for such polar states is of crucial importance for expanding materials' functionality. Here we report micro-focused angle-resolved photoemission spectroscopy of CsV3Sb5, a member of recently discovered kagome superconductors AV3Sb5 (A = K, Rb, Cs), and show evidence for the polar nature of cleaved surface which is characterized by Cs- and Sb-terminated surfaces with markedly different fermiology. The Cs-terminated surface shows intriguing doubling of V-derived bands at low temperature associated with the band folding due to the three-dimensional charge-density wave (CDW), whereas the Sb-terminated one shows no band doubling or resultant CDW-gap opening indicative of the suppression of bulk-originated CDW due to polar charge. Such polar-surface-dependent band structure must be incorporated for understanding the origin of unconventional superconducting and charge order at the surface of AV3Sb5.
@article{arxiv.2209.14556,
title = {Polarity-dependent charge-density wave in a kagome superconductor CsV3Sb5},
author = {Takemi Kato and Yongkai Li and Kosuke Nakayama and Zhiwei Wang and Seigo Souma and Miho Kitamura and Koji Horiba and Hiroshi Kumigashira and Takashi Takahashi and Takafumi Sato},
journal= {arXiv preprint arXiv:2209.14556},
year = {2022}
}