Spintronics in Half-Passivated Graphene

In this thesis, I propose a practical way to stabilize half passivated graphene (graphone). I show that the dipole moments induced by a hexagonal-boron nitride (h-BN) substrate on graphene stabilize the hydrogen atoms on one sublattice of the graphene layer and suppress the migration of the adsorbed hydrogen atoms. I also present the substrate effect of h-BN that reduces distortion induced by fluorination of graphene and stabilizes half-passivated graphene in a single sublattice. Then using spin-polarized density functional calculations I investigate magnetic properties of graphone. I show the system has different magnetic order which can be described by either super-exchange or double exchange mechanisms depending on the type of add atom. The hybridization of graphene changes from sp^2- to sp^3- type hybridization due to the buckling induced by passivation. The change in hybridization together with add-atom orbitals induces a fairly large spin orbit coupling (SOC). Based upon first principle spin-polarized density of states calculations, I show that the graphone obtained in different graphene/h-BN heterostructures exhibits a half metallic state. I propose to use this exotic material for spin valve systems and other spintronics devices

Spinmotive force due to motion of magnetic bubble arrays driven by magnetic field gradient

Interaction between local magnetization and conduction electrons is responsible for a variety of phenomena in magnetic materials. It has been recently shown that spin current and associated electric voltage can be induced by magnetization that depends on both time and space. This effect, called spinmotive force, provides for a powerful tool for exploring the dynamics and the nature of magnetic textures, as well as a new source for electromotive force. Here we theoretically demonstrate the generation of electric voltages in magnetic bubble array systems subjected to a magnetic field gradient. It is shown by deriving expressions for the electric voltages that the present system offers a direct measure of phenomenological parameter that describes non-adiabaticity in the current induced magnetization dynamics. This spinmotive force opens a door for new types of spintronic devices that exploit the field-gradient.Comment: accepted in Scientific Report

A stable path to ferromagnetic hydrogenated graphene growth

In this paper, we propose a practical way to stabilize half-hydrogenated graphene (graphone). We show that the dipole moments induced by an hexagonal-boron nitride (h-BN) substrate on graphene stabilize the hydrogen atoms on one sublattice of the graphene layer and suppress the migration of the absorbed hydrogen atoms. Based upon first principle spin polarized density of states (DOS) calculations, we show that the half hydrogenated graphene (graphone) obtained in different graphene-h-BN heterostructures exhibits a half metallic state. We propose to use this new exotic material for spin valve and other spintronics devices and applications.Comment: 8 pages, 8 figure