Quantum transport through 3D Dirac materials

TL;DR

This paper investigates quantum transport in 3D Dirac materials like bismuth alloys, analyzing conductance and electron behavior at interfaces using Landauer-B"uttiker formalism, revealing conditions for transparency and spin reversal effects.

Contribution

It provides a detailed analysis of quantum transport properties in 3D Dirac materials, including conductance calculations and spin effects at interfaces, which are novel insights in this context.

Findings

3DDM can be transparent to electrons under certain conditions

Electrons can reverse spin upon entering 3DDM at oblique incidence

Second interface cancels spin reversal effects

Abstract

Bismuth and its alloys provide a paradigm to realize three dimensional materials whose low-energy effective theory is given by Dirac equation in 3+1 dimensions. We study the quantum transport properties of three dimensional Dirac materials within the framework of Landauer-B\"uttiker formalism. Charge carriers in normal metal satisfying the Schr\"odinger equation, can be split into four-component with appropriate matching conditions at the boundary with the three dimensional Dirac material (3DDM). We calculate the conductance and the Fano factor of an interface separating 3DDM from a normal metal, as well as the conductance through a slab of 3DDM. Under certain circumstances the 3DDM appears transparent to electrons hitting the 3DDM. We find that electrons hitting the metal-3DDM interface from metallic side can enter 3DDM in a reversed spin state as soon as their angle of incidence deviates from the the direction perpendicular to interface. However the presence of a second interface completely cancels this effect.