Double refraction and spin splitter in a normal-hexagonal semiconductor junction

TL;DR

This paper proposes a model for double refraction and focusing of electrons in a normal-hexagonal semiconductor junction, enabling spin splitting based on valley-dependent negative refraction, with potential applications in spintronics.

Contribution

It introduces a novel model demonstrating double refraction and focusing in semiconductor junctions, and designs a spin splitter leveraging valley-dependent negative refraction.

Findings

Double refraction can be positive or negative depending on junction type.

A spin splitter is designed using valley-dependent negative refraction.

Potential applications in electronic lenses and spintronics.

Abstract

In analogy with light refraction at optical boundary, ballistic electrons also undergo refraction when propagate across a semiconductor junction. Establishing a negative refractive index in conventional optical materials is difficult, but the realization of negative refraction in electronic system is conceptually straightforward, which has been verified in graphene p-n junctions in recent experiments. Here, we propose a model to realize double refraction and double focusing of electric current by a normal-hexagonal semiconductor junction. The double refraction can be either positive or negative, depending on the junction being n-n type or p-n type. Based on the valley-dependent negative refraction, a spin splitter (valley splitter) is designed at the p-n junction system, where the spin-up and spin-down electrons are focused at different regions. These findings may be useful for the engineering of double lenses in electronic system and have underlying application of spin splitter in spintronics.