Dominant orbital magnetization in the prototypical altermagnet MnTe

TL;DR

This study reveals that the altermagnet MnTe exhibits a dominant orbital magnetization over spin magnetization, with spin contributions tunable by doping, emphasizing the importance of orbital effects in altermagnetic properties.

Contribution

The paper provides the first detailed density functional theory analysis of the intrinsic spin and orbital magnetization in MnTe, highlighting the dominance of orbital magnetization in altermagnets.

Findings

Orbital magnetization in MnTe is significantly larger than spin magnetization.

Spin magnetization can be tuned via hole doping.

Orbital magnetization remains stable against carrier density variations.

Abstract

Altermagnetism is an unconventional form of antiferromagnetism characterized by momentum-dependent spin polarization of electronic states and zero net magnetization, arising from specific crystalline symmetries. In the presence of spin-orbit coupling (SOC) and broken time-reversal symmetry, altermagnets can exhibit finite net magnetization and anomalous Hall effect (AHE), phenomena typically associated with ferromagnets. Due to the dependence of AHE on magnetization, understanding the interplay between spin and orbital contributions to magnetization is essential for interpreting experiments and designing altermagnetic devices. In this work, we use density functional theory to investigate the intrinsic spin and orbital magnetization of the magnetic ground state of the prototypical altermagnet {\alpha}-MnTe. We find that SOC induces weak ferromagnetism through spin canting, accompanied by a slight in-plane rotation of the N\'eel vector. Notably, we identify a significant net orbital magnetization of 0.176 {\mu}B per unit cell oriented along the z-axis, while the spin magnetization in the same direction is much smaller at 0.002 {\mu}B. By varying the chemical potential, we show that the spin magnetization is tunable through hole doping, whereas the orbital magnetization remains robust against carrier density changes. These results highlight the important role of orbital magnetization and establish its relevance for orbital-based phenomena in altermagnets.