Multiple Quantum Phases in Graphene with Enhanced Spin-Orbit Coupling: From Quantum Spin Hall Regime to Spin Hall Effect and Robust Metallic State

Alessandro Cresti, Dinh Van Tuan, David Soriano, Aron W. Cummings, Stephan Roche

Published 2014-11-21Version 1

We report an intriguing transition from the Quantum Spin Hall phase to Spin Hall Effect upon segregation of thallium adatoms adsorbed onto a graphene surface. Landauer-B\"uttiker and Kubo-Greenwood simulations are used to access both edge and bulk transport physics in disordered thallium-functionalized graphene systems of realistic sizes. Our findings quantify the detrimental effects of adatom clustering in the formation of the topological state, but also provide evidence for the emergence of spin accumulation at opposite sample edges driven by spin-dependent scattering induced by thallium islands, which eventually result in a minimum bulk conductivity $\sim 4e^{2}/h$, insensitive to localization effects.