Adiabatic quantum pumping in graphene with magnetic barriers

TL;DR

This paper investigates how adiabatic quantum pumping can generate valley-polarized currents in graphene with magnetic barriers, using scattering matrix methods and considering various barrier configurations.

Contribution

It introduces a model for quantum pumping in graphene with magnetic barriers, including valley polarization effects and analytical solutions for certain barrier types.

Findings

Valley-polarized currents can be pumped due to valley symmetry breaking.

Analytical expressions are derived for delta-function magnetic barriers.

Numerical results compare different magnetic barrier configurations.

Abstract

We study an adiabatic quantum pump effect in a two terminal graphene device with two oscillating square electric barriers and a stationary magnetic barrier using the scattering matrix approach. The model employs the low-energy Dirac approximation and incorporates the possible existence of a finite band gap in graphene spectrum. We show that in this case valley-polarized and pure valley currents can be pumped due to the valley symmetry breaking. For a \delta-function magnetic barrier we present analytical expressions for bilinear total and valley pumping responses. These results are compared to numerical ones for a double \delta-function, a square and a triple square magnetic barriers.