Spin Relaxation in Strained Graphene-TMD Heterostructures using Ab Initio Methods

While graphene is a compelling candidate for spintronics due to weak spin-orbit coupling (SOC), adding strain and transition metal dichalcogenide (TMD) (MoSe₂, WS₂) monolayers allows for preferentially modulated SOC in graphene-based spintronics devices. Previous work includes ab initio studies of SOC in twisted graphene/TMD layers along with studies of spin relaxation in intrinsic, strained graphene structures. However, systematic studies of SOC in strained graphene-TMD nanostructures are currently lacking. Additionally, SOC combined with momentum relaxation models is crucial to quantifying spin relaxation times in these nanostructures. In this work, we use ab initio calculations to obtain spin relaxation times in strained graphene-TMD nanoribbons and elucidate the role of strain/TMD-induced band structure features and scattering mechanisms on spin lifetimes. Density Functional Theory (DFT) calculations were performed with strained graphene/TMD heterostructure supercells. SOC constants were then extracted by fitting DFT band structure calculations to a strained Hamiltonian model with orbital and spin-orbital components. DFT band structures were also used to determine momentum relaxation times based on phonon, coulombic impurity, and defect scattering mechanisms. We then present spin relaxation times computed via Eliot-Yafet and D’yakonov Perel spin relaxation mechanisms in strained, graphene-TMD nanoribbons.