Stoichiometry-induced ferromagnetism in altermagnetic candidate MnTe

TL;DR

This study demonstrates that the electronic and magnetic properties of MnTe thin films are strongly influenced by stoichiometry, revealing ferromagnetism linked to Mn-richness and highlighting potential for spintronic applications.

Contribution

It shows that natural stoichiometry in MnTe films induces ferromagnetism, providing new insights into controlling altermagnetic order in spintronics.

Findings

MnTe films are natively metallic with Fermi level in the valence band.

Weak ferromagnetism is linked to Mn-richness in MBE-grown samples.

Electronic response is strongly affected by ferromagnetic moments.

Abstract

The field of spintronics has seen a surge of interest in altermagnetism due to novel predictions and many possible applications. MnTe is a leading altermagnetic candidate that is of significant interest across spintronics due to its layered antiferromagnetic structure, high Neel temperature (TN ~ 310 K) and semiconducting properties. We present results on molecular beam epitaxy (MBE) grown MnTe/InP(111) films. Here, it is found that the electronic and magnetic properties are driven by the natural stoichiometry of MnTe. Electronic transport and in situ angle-resolved photoemission spectroscopy show the films are natively metallic with the Fermi level in the valence band and the band structure is in good agreement with first principles calculations for altermagnetic spin-splitting. Neutron diffraction confirms that the film is antiferromagnetic with planar anisotropy and polarized neutron reflectometry indicates weak ferromagnetism, which is linked to a slight Mn-richness that is intrinsic to the MBE grown samples. When combined with the anomalous Hall effect, this work shows that the electronic response is strongly affected by the ferromagnetic moment. Altogether, this highlights potential mechanisms for controlling altermagnetic ordering for diverse spintronic applications.