Anomalous, spin, and valley Hall effects in graphene deposited on ferromagnetic substrates

TL;DR

This paper theoretically investigates how proximity effects from magnetic substrates influence spin, anomalous, and valley Hall effects in graphene, revealing universal conductivities within energy gaps.

Contribution

It introduces effective Hamiltonians for hybrid graphene systems and analyzes the impact of proximity-induced exchange and spin-orbit coupling on Hall effects.

Findings

Proximity effects significantly alter electronic and spin transport in graphene.

Universal Hall conductivities are observed within the energy gap.

Different hybrid structures exhibit distinct Hall responses.

Abstract

Spin, anomalous, and valley Hall effects in graphene-based hybrid structures are studied theoretically within the Green function formalism and linear response theory. Two different types of hybrid systems are considered in detail: (i) graphene/boron nitride/cobalt(nickel), and (ii) graphene/YIG. The main interest is focused on the proximity-induced exchange interaction between graphene and magnetic substrate and on the proximity-enhanced spin-orbit coupling. The proximity effects are shown to have a significant influence on the electronic and spin transport properties of graphene. To find the spin, anomalous and valley Hall conductivities we employ certain effective Hamiltonians which have been proposed recently for the hybrid systems under considerations. Both anomalous and valley Hall conductivities have universal values when the Fermi level is inside the energy gap in the electronic spectrum.