Large anisotropic magnetoresistance in $\alpha$-MnTe induced by strain

Abstract

$\alpha \text{-MnTe}$ is a p-type semiconducting altermagnet with a Néel temperature near $300\text{K}$. Due to the altermagnetic nature, $\mathcal{P}\mathcal{T}$ symmetry is broken, and Kramers degeneracy is lifted in the valence band maxima along the $\Gamma \text{-K}$ line and the A point. However, the energy difference is found to be small, and any small shift in the spectrum can dramatically change the linear-response transport properties. Here we show that a strain modulating the [0001] axis of the unit cell by $\sim \pm 0.5\%$ can significantly change the transport signature by switching the thermal window between the two regions of the valence band. When the $\Gamma \text{-K}$ line is dominating, the planar Hall effect and the anisotropic magnetoresistance can be enhanced by an order of magnitude, with the maximum up to $\sim 70\%$.

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