Surface-termination-dependent electronic states in kagome superconductors <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mrow><mml:mi>A</mml:mi><mml:mi mathvariant="normal">V</mml:mi></mml:mrow><mml:mn>3</mml:mn></mml:msub><mml:msub><mml:mi>Sb</mml:mi><mml:mn>5</mml:mn></mml:msub></mml:mrow></mml:math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>(</mml:mo><mml:mi>A</mml:mi><mml:mo>=</mml:mo><mml:mi mathvariant="normal">K</mml:mi><mml:mo>,</mml:mo><mml:mo> </mml:mo><mml:mi>Rb</mml:mi><mml:mo>,</mml:mo><mml:mo> </mml:mo><mml:mi>Cs</mml:mi><mml:mo>)</mml:mo></mml:mrow></mml:math> studied by micro-ARPES
Takemi Kato, Yongkai Li, Min Liu, K. Nakayama, Zhiwei Wang, S. Souma, Miho Kitamura, Koji Horiba, Hiroshi Kumigashira, Takashi Takahashi, Yugui Yao, T. Sato
Abstract
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 $A{\text{V}}_{3}{\text{Sb}}_{5}$.