Electronic inhomogeneity in Cs- and Sb-terminated surfaces of CsV$_3$Sb$_5$ probed by scanning photoemission spectromicroscopy

Abstract

Electronic structures of Cs- and Sb-terminated surfaces of a kagome superconductor CsV$_3$Sb$_5$ have been elucidated by means of scanning photoemission microscopy (SPEM). The observed band structure of the Cs-terminated surface is rather close to that of the bulk while that of the Sb-terminated one is substantially modified around K/H point of the Brillouin zone. While the contrast between the Cs- and Sb-terminated regions is reduced below the charge density wave transition temperature, the Sb 5$p$ band of Cs-terminated region exhibits electronic inhomogeneity which slightly increases below it. The inhomogeneity of the Sb 5$p$ band would be related to disorders of the out-of-plane Sb and relevant for the band folding along $\Gamma$-A with the charge density wave. The SPEM results suggest that the less inhomogeneous Cs termination is more suitable for interface of kagome superconductors. However, the inhomogeneity of Cs termination, which is significant at $\Gamma$/A, noticeable at K/H, and negligible at M/L, is expected to affect the Sb 5$p$-V 3$d$ hybridization at the interface.