Spin Polarization via Electron Tunneling through an Indirect-Gap Semiconductor Barrier

TL;DR

This paper investigates spin-dependent electron tunneling through indirect-gap semiconductor barriers, highlighting the potential for high spin polarization and filtering applications based on material properties and spin-orbit interactions.

Contribution

It introduces a detailed analysis of spin tunneling through X-point barriers, emphasizing the role of linear-k spin-orbit splitting and calculating the spin splitting coefficient for various semiconductors.

Findings

High spin polarization achievable in certain materials

Linear-k spin-orbit splitting influences tunneling behavior

Potential for spin filter applications

Abstract

We study the spin dependent tunneling of electrons through a zinc-blende semiconductor with the indirect X (or D) minimum serving as the tunneling barrier. The basic difference between tunneling through the G vs. the X barrier is the linear-k spin-orbit splitting of the two spin bands at the X point, as opposed to the k3 Dresselhaus splitting at the G point. The linear coefficient of the spin splitting b at the X point is computed for several semiconductors using density-functional theory and the transport characteristics are calculated using the barrier tunneling model. We show that both the transmission coefficient as well as the spin polarization can be large, suggesting the potential application of these materials as spin filters.