Surface-termination-dependent electronic states in kagome superconductors AV₃Sb₅ (A = K, Rb, Cs) studied by micro-ARPES

Recently discovered kagome superconductors AV(3)Sb(5) (A = K, Rb, Cs) exhibit exotic bulk and surface physical properties such as charge density wave (CDW) and chirality, whereas their origins remain unresolved. By using microfocused angle-resolved photoemission spectroscopy, we discovered that AV(3)Sb(5) commonly exhibits two distinct polar surfaces depending on the termination: electron- and hole-doped ones for the A and Sb termination, respectively. We observed that the kagome-derived band shows a splitting in the A-terminated surface, while it is absent in the Sb-terminated counterpart, suggestive of a signature of the polarity-dependent CDW at the surface. Close comparison of the band-dependent splitting implies that the three-dimensional CDW structure of the K-terminated surface is different from that of the Rb- or Cs-terminated surface, suggesting the possible diversity of the CDW ground state. These results provide important insight into the origin of CDW in kagome superconductors AV(3)Sb(5).