Weak Electron-Phonon Coupling and Unusual Electron Scattering of Topological Surface States in Sb(111) by Laser-Based Angle-Resolved Photoemission Spectroscopy

摘要

High resolution laser-based angle-resolved photoemission measurements havebeen carried out on Sb(111) single crystal. Two kinds of Fermi surface sheetsare observed that are derived from the topological surface states: one smallhexagonal electron-like Fermi pocket around $\Gamma$ point and the other sixelongated lobes of hole-like Fermi pockets around the electron pocket. ClearRashba-type band splitting due to the strong spin-orbit coupling is observedthat is anisotropic in the momentum space. Our super-high-resolution ARPESmeasurements reveal no obvious kink in the surface band dispersions indicatinga weak electron-phonon interaction in the surface states. In particular, theelectron scattering rate for these topological surface states is nearly aconstant over a large energy window near the Fermi level that is unusual interms of the conventional picture.