Local electronic properties of the graphene-protected giant Rashba-split BiAg₂ surface

Abstract

We report the preparation of an interface between graphene and a strong Rashba-split BiAg2 surface alloy and an investigation of its structure as well as the electronic properties by means of scanning tunneling microscopy/spectroscopy and density functional theory calculations. Upon evaluation of the quasiparticle interference patterns, an unperturbed linear dispersion for the π band of n-doped graphene is observed. Our results also reveal the intact nature of the giant Rashba-split surface states of the BiAg2 alloy, which demonstrate only a moderate downward energy shift due to the presence of graphene. This effect is explained in the framework of density functional theory by an inward relaxation of the Bi atoms at the interface and subsequent delocalization of the wave function of the surface states. Our findings demonstrate a realistic pathway to prepare a graphene-protected giant Rashba-split BiAg2 for possible spintronic applications.