Ballistic transverse magnetic focusing in monolayer graphene on WSe₂

It has been found that a large spin-orbit coupling (SOC) is induced in monolayer graphene by proximity with transition metal dichalcogenides (TMDC), as compared to the very weak one in pristine graphene. Theoretical calculation showed that the SOC splits the monolayer band and there exist two types: the valley-Zeeman term which couples the out-of-plane spin and valley degrees of freedom, and the Rashba term which couples the in-plane spin and sublattice degrees of freedom. Here we employ the transverse magnetic focusing technique to probe the effects of the SOC on the Fermi surface profile and electron dynamics in monolayer graphene-TMDC heterostructure. We clearly observed the spin-split band in graphene on WSe₂, and quantitively estimated the sizes of both SOC terms by analyzing the TMF peaks. Interestingly, the second TMF peak didn’t show the splitting and theoretical analysis further shows that this is closely related to the effect of scattering at the sample edges and the spin conservation.