Spin polarization and Fano–Rashba resonance in nonmagnetic graphene

Abstract

We study the symmetry of spin transport in graphene with the Rashba spin–orbit coupling (SOC) and the staggered potential, which can be produced by depositing the graphene on a transition-metal dichalcogenides substrate. The results show that all three spin polarization components along the x, y and z directions are achieved with a measurable conductance in such a nonmagnetic graphene. The spin transport property near the two valleys is discussed in the light of the symmetry of the system. Both conductance and spin polarization present some certain symmetries with respect to the Rashba SOC (RSOC) and staggered potential. The system could work as a valley-spin polarization transverter which combines valleytronics and spintronics. Furthermore, the asymmetric Fano–Rashba resonance of the conductance and spin polarization could occur in a resonant structure due to interference of spin-polarized discrete and continuum states induced by the RSOC. The Fano–Rashba resonance can be effectively controlled by the gate voltage. The derived symmetry relations and numerical results could provide a guideline for the design of spin-valley-based devices.