Ballistic Spin Injection from Fe into ZnSe and GaAs with a (001), (111), and (110) orientation

TL;DR

This study uses first-principles calculations to analyze how the orientation of Fe/semiconductor interfaces affects spin injection efficiency, highlighting the importance of symmetry mismatch and interface states.

Contribution

It provides a detailed comparison of spin injection efficiencies across different interface orientations and the effects of interface states and bias.

Findings

(001) interface shows high spin polarization due to symmetry mismatch.

(111) and (110) interfaces have lower spin injection efficiencies.

Interface states reduce overall spin polarization.

Abstract

We present first-principles calculations of ballistic spin injection in Fe/GaAs and Fe/ZnSe junctions with orientation (001), (111), and (110). We find that the symmetry mismatch of the Fe minority-spin states with the semiconductor conduction states can lead to extremely high spin polarization of the current through the (001) interface for hot and thermal injection processes. Such a symmetry mismatch does not exist for the (111) and (110) interfaces, where smaller spin injection efficiencies are found. The presence of interface states is found to lower the current spin polarization, both with and without a Schottky barrier. Finally, a higher bias can also affect the spin injection efficiency.