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Abstract:

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The two-dimensional (2D) kagome superconductor CsV3Sb5 has attracted much recent attention due to the coexistence of superconductivity, charge orders, topology and kagome physics, which manifest themselves as distinct electronic structures in both bulk and surface states of the material. An interesting next step is to manipulate the electronic states in this system. Here, we report angle-resolved photoemission spectroscopy (ARPES) evidence for a surface-induced orbital-selective band reconstruction in CsV3Sb5. A significant energy shift of the electron-like band around &Gamma; and a moderate energy shift of the hole-like band around M are observed as a function of time. This evolution is reproduced in a much shorter time scale by in-situ annealing of the CsV3Sb5 sample. Orbital-resolved density functional theory (DFT) calculations reveal that the momentum-dependent band reconstruction is associated with different orbitals for the bands around &Gamma; and M, and the time-dependent evolution points to the change of sample surface that is likely caused by the formation of Cs vacancies on the surface. Our results indicate the possibility of orbital-selective control of the band structure via surface modification, which may open a new avenue for manipulating exotic phenomena in this material system, including superconductivity.
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