Spin tunneling through an indirect barrier

TL;DR

This paper investigates spin-dependent tunneling through an indirect bandgap barrier using tight-binding methods, revealing conditions for large spin polarization in specific energy windows.

Contribution

It introduces a novel analysis of spin tunneling in indirect barriers and formulates conditions for achieving high spin polarization.

Findings

Large spin polarization achievable in certain energy windows.

Proportionality of Dresselhaus Hamiltonians at $\Gamma$ and $X$ points is key.

Conditions for existence of high polarization energy windows are established.

Abstract

Spin-dependent tunneling through an indirect bandgap barrier like the GaAs/AlAs/GaAs heterostructure along [001] direction is studied by the tight-binding method. The tunneling is characterized by the proportionality of the Dresselhaus Hamiltonians at $\Gamma $ and $X$ points in the barrier and by Fano resonances. The present results suggest that large spin polarization can be obtained for energy windows that exceed significantly the spin splitting. We also formulate two conditions that are necessary for the existence of energy windows with large polarization.