Spin-and Valley-Dependent Transport in Hybrid System and 2D Dirac Materials.

Abstract

In this thesis, we aim to study the spin- and valley-dependent transport in hybrid system and twodimensionalDirac materials.In the first part, I study some spin-dependent and phase-coherent phenomena in hybrid structures.First, I present a full microscopic theory of the spin Hall magnetoresistance (SMR) in non-magneticmetal/magnetic insulator heterostructures. As examples, we apply it into both paramagnetic andferromagnetic SMR, specifically Platinum/Gd3Ga5O12 (Pt/GGG) and Platinum/Europium sulfide(Pt/EuS), respectively. Furthermore, if non-magnetic metal is replaced by nanowire in proximity tosuperconductor below the critical temperature, we can study the interplay of magnetic andsuperconducting proximity effects.In the second part, I explore the possible mechanisms responsible for the classical versions of spinand valley Hall effects, and proposed the schemes for experimental detection of these effects bynonlocal resistance measurements. The understanding of the magnetic properties of nonlocalresistance is significant for the recent controversy about the physical origin of nonlocal resistancemeasured in Hall bar devices made of graphene decorated with absorbates, where the presence oflarge nonlocal resistance and the absence of Hanle oscillation, that is, an oscillation of the nonlocalresistance with in-plane magnetic field, suggest the possibility of the new origin of nonlocalresistance insensitive to magnetic field.