Determining spin-orbit coupling in graphene by quasiparticle interference imaging

We deploy quasi-particle interference imaging using a scanning tunneling microscope to probe the presence, nature and strength of proximity induced spin-orbit coupling (SOC) in single layer graphene (SLG) on WSe₂. In the presence of SOC, the pseudo-spin texture is modified, enabling intravalley backscattering normally forbidden in SLG. This backscattering is detected by a characteristic small momentum ring around the gamma point in the Fourier transforms of conductance maps. Fitting the intensity of this ring to a weak coupling Hamiltonian, we can identify the contribution of a Rashba and a valley-Zeeman SOC term, and exclude the contribution of a mass gap to the observed intravalley backscattering.

Collaboration with Alberto Morpurgo and Louk Rademaker, University of Geneva.