Graphene p-n junctions with nonuniform Rashba spin-orbit coupling

TL;DR

This paper theoretically investigates how nonuniform Rashba spin-orbit coupling affects the electronic conductance of graphene p-n junctions, revealing significant modifications including an anomalous conductance minimum.

Contribution

It introduces a model for nonuniform Rashba coupling in graphene p-n junctions and analyzes its impact on conductance, highlighting novel effects not previously described.

Findings

Conductance is significantly affected by Rashba nonuniformity.

An anomalous minimum in conductance occurs at specific potential steps.

Nonuniform Rashba coupling can be induced by asymmetric layering or electric fields.

Abstract

Linear conductance of graphene-based p-n junctions with Rashba spin-orbit coupling is considered theoretically. A square potential step is used to model the junctions, while the coupling is introduced in terms of the Kane-Mele model (C.L. Kane and E.J. Mele, Phys.Rev.Lett. 95, 226801(2005)). The main objective is a description of electronic transport in junctions where Rashba parameter is nonuniform. Such a nonuniformity can appear when graphene is asymmetrically covered with atomic layers, or when Rashba coupling is strongly dependent on electric field. It is shown that conductance is significantly modified by the considered nonuniformity, which is most clearly manifested by an anomalous minimum at a certain potential step height.