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

Recently discovered kagome superconductors $A{\text{V}}_{3}{\text{Sb}}_{5}$ $(A=\mathrm{K}, \mathrm{Rb}, \mathrm{Cs})$ 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 $A{\text{V}}_{3}{\text{Sb}}_{5}$ 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 $A{\text{V}}_{3}{\text{Sb}}_{5}$.