Magnetization symmetry for the MnTe altermagnetic candidate

TL;DR

This study explores the unique magnetization angle dependence in MnTe, revealing behaviors that support its classification as an altermagnetic material with unconventional symmetry properties.

Contribution

It provides experimental evidence of magnetization symmetry in MnTe, supporting its altermagnetic ground state and revealing unusual angular dependence not typical of standard antiferromagnets.

Findings

Magnetization exhibits a sharp jump at 81 K.

Easy magnetization axis rotates by π/2 with field or temperature change.

Magnetization symmetry aligns with altermagnetic ground state evidence.

Abstract

We experimentally investigate the magnetization angle dependence $M(\alpha)$ for single crystals of MnTe altermagnetic candidate. In high magnetic fields, experimental $M(\alpha)$ curves mostly reflect standard antiferromagnetic spin-flop processes, which are allowed below the N\'eel vector reorientation field. In low magnetic fields and at low temperatures, spontaneous magnetization appears as a sharp $M(T)$ magnetization jump around 81~K. In this regime, $M(\alpha)$ dependence is quite unusual: the easy magnetization axis is $\pi/2$ rotated either by increasing the field above 1~kOe or the temperature above 81~K. The observed behavior cannot be expected for antiferromagnetics, e.g. it differs strongly from the well known weak ferromagnetism. Thus, it requires to take into account the formation of the altermagnetic ground state for MnTe altermagnetic candidate. Despite MnTe is expected to have g-wave order parameter, $M(\alpha)$ magnetization symmetry confirms the prevailing population of one from three easy axes, as it has been shown previously by temperature-dependent angle-resolved photo-emission spectroscopy.