Direct Observation of Antiferromagnetic Parity Violation in the Electronic Structure of Mn$_2$Au

TL;DR

This paper reports the first direct experimental observation of antiferromagnetic parity violation in the electronic band structure of Mn$_2$Au, using advanced momentum microscopy techniques to resolve single-domain effects.

Contribution

It introduces a novel experimental approach combining momentum microscopy and ab-initio calculations to observe and image parity violation and Neel vector orientation in antiferromagnetic materials.

Findings

Observation of antiferromagnetic parity violation in Mn$_2$Au

Demonstration of momentum microscopy for single-domain analysis

Method for imaging Neel vector direction

Abstract

Parity symmetric photoemission spectra are ubiquitous in solid state research, being prevalent in many highly active areas, such as unconventional superconductors, nonmagnetic and antiferromagnetic topological insulators, and weakly relativistic collinear magnets, among others. The direct observation of parity-violating metallic Kramers degenerate bands has remained hitherto experimentally elusive. Here we observe the antiferromagnetic parity violation (APV) in the bandstructure of Mn$_2$Au thin films by using momentum microscopy with sub-$mu$m spatial resolution, allowing momentum resolved photoemission on single antiferromagnetic domains. The APV arises from breaking the P symmetry of the underlying crystal structure by the collinear antiferromagnetism, while preserving the joint space-time inverison PT -symmetry and in combination with large spin-orbit coupling. In addition, our work also demonstrates a novel tool to directly image the Neel vector direction by combining spatially resolved momentum microscopy with ab-initio calculations.