Magnetic ratchet effect in bilayer graphene

TL;DR

This paper investigates how in-plane magnetic fields influence bilayer graphene, revealing a significant ratchet effect that could enhance optoelectronic applications by exploiting inversion-symmetry breaking.

Contribution

It derives linear-in-field Hamiltonian terms for bilayer graphene and demonstrates the potential for a strong ratchet effect surpassing monolayer graphene.

Findings

The ratchet effect in bilayer graphene can be two orders of magnitude greater than in monolayer.

Inversion-symmetry breaking enhances the magnetic field's orbital effects.

Bilayer graphene is an ideal platform for optoelectronic devices exploiting this effect.

Abstract

We consider the orbital effect of an in-plane magnetic field on electrons in bilayer graphene, deriving linear-in-field contributions to the low-energy Hamiltonian arising from the presence of either skew interlayer coupling or interlayer potential asymmetry, the latter being tunable by an external metallic gate. To illustrate the relevance of such terms, we consider the ratchet effect in which a dc current results from the application of an alternating electric field in the presence of an in-plane magnetic field and inversion-symmetry breaking. By comparison with recent experimental observations in monolayer graphene [C. Drexler et al., Nature Nanotech. 8, 104 (2013)], we estimate that the effect in bilayer graphene can be two orders of magnitude greater than that in monolayer, illustrating that the bilayer is an ideal material for the realization of optoelectronic effects that rely on inversion-symmetry breaking.