Theory of the Anomalous Tunnel Hall Effect at Ferromagnet-Semiconductor Junctions

TL;DR

This paper provides a theoretical analysis of the Anomalous Tunnel Hall Effect at ferromagnet-semiconductor junctions, revealing transmission asymmetries caused by spin-orbit interactions and their implications for spin-current induced transverse charge currents.

Contribution

It introduces a multiband tunneling model demonstrating the universal asymmetry in transmission and the existence of the Anomalous Tunnel Hall Effect in such junctions.

Findings

Transmission asymmetry depends on Dresselhaus spin-orbit interactions.

Asymmetry persists in the valence band due to atomic spin-orbit strength.

Tunnel spin-current can generate a transverse charge current.

Abstract

We report on theoretical investigations of carrier scattering asymmetry at ferromagnet-semiconductor junctions. By an analytical $2\times 2$ spin model, we show that, when Dresselhaus interactions is included in the conduction band of III-V $T_d$ symmetry group semiconductors, the electrons may undergo a difference of transmission vs. the sign of their incident parallel wavevector normal to the in-plane magnetization. This asymmetry is universally scaled by a unique function independent of the spin-orbit strength. This particular feature is reproduced by a multiband $\mathbf{k}\cdot \mathbf{p}$ tunneling transport model. Astonishingly, the asymmetry of transmission persists in the valence band of semiconductors owing to the inner atomic spin-orbit strength and free of asymmetric potentials . We present multiband $14\times 14$ and $30\times 30$ $\mathbf{k}\cdot \mathbf{p}$ tunneling models together with tunneling transport perturbation calculations corroborating these results. Those demonstrate that a tunnel spin-current normal to the interface can generate a surface transverse charge current, the so-called Anomalous Tunnel Hall Effect.