Scanning Tunneling Spectroscopic Studies of Surface States on Emergent Topological Insulator BiTeI*

We use scanning tunneling microscopy and spectroscopy to investigate the emergent topological insulator BiTeI. We discover three different kinds of surfaces where the Fermi level lies above, below, and inside the band gap. By imaging the real- and momentum-space differential conductance, we observe charging effects of acceptor-type defects, as well as quasiparticle interference (QPI) up to 1.2 eV above the Fermi level. Furthermore, QPI modes reveal the absence of backscattering, which implies that Rashba spin splitting persists up to this high energy.