Effective Medium Model for Graphene Superlattices with Electrostatic and Magnetic Vector Potentials

TL;DR

This paper develops an effective medium model to analyze electron wave propagation in graphene superlattices with electrostatic and magnetic potentials, revealing tunable nonreciprocal responses and Dirac cone types.

Contribution

The paper introduces a numerical effective medium approach to characterize and control electron dispersion in graphene superlattices with combined electrostatic and magnetic potentials.

Findings

Superlattices with magnetic potential alone show reciprocal response and reduced charge velocity.

Combined potentials induce nonreciprocal dispersion with tilted Dirac cones.

Tuning potentials allows switching between different Dirac cone types.

Abstract

In this article we develop an effective medium model to characterize the electron wave propagation in graphene based nanostructures with an electrostatic and magnetic vector potentials imposed on their surface. We use a numerical algorithm to determine the effective medium parameters of the heterostructure and calculate the electronic band structure of the system. We apply our formalism to analyze superlattices with solely a magnetic potential and reveal that the response of the structure remains reciprocal and is characterized by a decrease in charge carrier's velocity. We also study the response of superlattices with both potentials superimposed on graphene and show that the response of the system becomes nonreciprocal with a dispersion characterized by a tilted Dirac cone. We demonstrate that it is possible to alternate between a type-I, type-II or type-III Dirac cones by properly tuning the amplitude of the potentials.