Spintronics in half-passivated graphene

TL;DR

This thesis explores stabilizing half-passivated graphene (graphone) using h-BN substrates, investigates its magnetic properties and spin-orbit coupling, and proposes its application in spintronics devices.

Contribution

It introduces a practical method to stabilize graphone with h-BN, analyzes its magnetic and electronic properties, and suggests potential spintronics applications.

Findings

h-BN stabilizes hydrogen on one sublattice of graphene

graphone exhibits half-metallic behavior in heterostructures

large spin-orbit coupling induced by passivation and hybridization

Abstract

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 the 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.