Structural Distortion Stabilizing the Antiferromagnetic and Semiconducting Ground State of BaMn$_2$As$_2$

TL;DR

This study reveals that a subtle tetragonal distortion stabilizes the antiferromagnetic and semiconducting ground state of BaMn$_2$As$_2$, linked to specific Wannier states at the Fermi level, suggesting a structural origin for its electronic properties.

Contribution

It demonstrates that a small tetragonal distortion is essential for stabilizing the antiferromagnetic semiconducting state in BaMn$_2$As$_2$, highlighting the role of Wannier states and structural effects.

Findings

Antiferromagnetic structure is linked to Wannier states at the Fermi level.

A tetragonal distortion stabilizes the semiconducting state.

The distortion has not yet been experimentally observed.

Abstract

We report evidence that the experimentally found antiferromagnetic structure as well as the semiconducting ground state of BaMn$_2$As$_2$ are caused by optimally-localized Wannier states of special symmetry existing at the Fermi level of BaMn$_2$As$_2$. In addition, we find that a (small) tetragonal distortion of the crystal is required to stabilize the antiferromagnetic semiconducting state. To our knowledge, this distortion has not yet been established experimentally.