Manipulation of spin transport in graphene/transition metal dichalcogenide heterobilayers upon twisting

Abstract

Altres ajuts: ZZ and NW acknowledge the computer resources at MareNostrum and the technical support provided by Barcelona Supercom- puting Center (FI-2020-1-0014). We acknowledge PRACE for awarding us access to MareNostrum 4 at Barcelona Supercomputing Center (BSC), Spain (OptoSpin project id. 2020225411)

Proximity effects between layered materials trigger a plethora of novel and exotic quantum transport phenomena. Besides, the capability to modulate the nature and strength of proximity effects by changing crystalline and interfacial symmetries offers a vast playground to optimize physical properties of relevance for innovative applications. In this work, we use large-scale first principles calculations to demonstrate that strain and twist-angle strongly vary the spin-orbit coupling in graphene/transition metal dichalcogenide heterobilayers. Such a change results in a modulation of the spin relaxation times by up to two orders of magnitude. Additionally, the relative strengths of valley-Zeeman and Rashba spin-orbit coupling can be tailored upon twisting, which can turn the system into an ideal Dirac-Rashba regime or generate transitions between topological states of matter. These results shed new light on the debated variability of spin-orbit coupling and clarify how lattice deformations can be used as a knob to control spin transport. Our outcomes also suggest complex spin transport in polycrystalline materials, due to the random variation of grain orientation, which could reflect in large spatial fluctuations of spin-orbit coupling fields