Spontaneous persistent currents in magnetically ordered graphene ribbons

TL;DR

This paper demonstrates that ferromagnetic order in graphene zigzag ribbons with spin-orbit coupling can induce spontaneous, dissipationless persistent charge currents at the edges, akin to those in topological insulators.

Contribution

It introduces a new mechanism for persistent charge currents in graphene ribbons driven by magnetic order, expanding understanding of topological and magnetic effects in 2D materials.

Findings

Identified three magnetic edge phases with persistent currents up to 0.4nA.

Showed that magnetic order converts spin currents into charge currents without external fields.

Discovered a phase that is a valley half-metal with potential spintronic applications.

Abstract

We present a new mechanism for dissipationless persistent charge current. Two dimensional topological insulators hold dissipationless spin currents in their edges so that, for a given spin orientation, a net charge current flows which is exactly compensated by the counter-flow of the opposite spin. Here we show that ferromagnetic order in the edge upgrades the spin currents into persistent charge currents, without applied fields. For that matter, we study an interacting graphene zigzag ribbon with spin-orbit coupling. We find three electronic phases with magnetic edges that carry currents reaching 0.4nA, comparable to persistent currents in metallic rings, for the small spin orbit coupling in graphene. One of the phases is a valley half-metal.