Giant strain-induced spin splitting effect in MnTe, a $g$-wave altermagnetic semiconductor

TL;DR

This paper demonstrates that elastic strain can induce significant spin splitting in MnTe, a g-wave altermagnetic semiconductor, enabling its use in spintronic devices by engineering substrate-induced strain.

Contribution

It introduces a strain-induced spin splitting mechanism in MnTe and develops a spin-orbit-coupled Hamiltonian fitted to first-principles data, highlighting potential spintronic applications.

Findings

Spin splitting angle exceeds 20 near the valence band maximum.

Elastic strain effectively induces spin splitting in MnTe.

Proper spin-orbit coupling inclusion is essential for accurate transport property description.

Abstract

Hexagonal MnTe is an altermagnetic semiconductor with $g$-wave symmetry of spin polarization in momentum space. In the nonrelativistic limit, this symmetry mandates that electric current flowing in any crystallographic direction is unpolarized. However, it is shown that elastic strain is effective in inducing the spin splitting effect in MnTe. For this analysis, a spin-orbit-coupled $\mathbf{k}\cdot\mathbf{p}$ Hamiltonian for the valence band maximum at the A point is derived and fitted to eigenvalues calculated from first principles. The spin splitting angle is calculated using the Boltzmann approach in the relaxation-time approximation. The spin splitting gauge factor exceeds 20 near the valence band maximum. Thus, with suitable substrate engineering, MnTe can be used as an efficient source and detector of spin current in spintronic devices. Proper inclusion of the Rashba-Dresselhaus spin-orbit coupling is crucial for the correct description of the transport properties of MnTe.