Correlated topological band structures of the kagome altermagnets Mn$_3X$ ($X=$ Sn, Ge, Ga)

TL;DR

This paper demonstrates that advanced correlation-aware computational methods are essential for accurately characterizing the topological and magnetic properties of kagome altermagnets Mn$_3X$, revealing their potential for enhanced anomalous Hall effects.

Contribution

It introduces a beyond-DFT approach to accurately model the magnetic, electronic, and topological properties of Mn$_3X$ altermagnets, challenging previous DFT-based interpretations.

Findings

Noncollinear altermagnetic orders are established.

Band structures align well with ARPES experiments.

Weyl nodes can be tuned, affecting Hall conductivity.

Abstract

The interplay of topological band structures and electronic correlations may lead to novel quantum phenomena with potential applications. First-principles calculations are critical for guiding experimental discoveries and interpretations, but often fail if electronic correlations cannot be properly treated. Here we show that this issue occurs also in the kagome altermagnets Mn$_3X$ ($X=$ Sn, Ge, Ga), which were believed to exhibit large anomalous Hall effect due to topological band structures with Weyl nodes near the Fermi energy. Our systematic investigations reveal critical importance of beyond-DFT treatments on three key aspects of their magnetic, electronic, and topological properties: (1) establishment of noncollinear altermagnetic orders, (2) weakly renormalized band structures in excellent agreement with angle-resolved photoemission spectroscopy experiment, and (3) sensitive tuning of the Weyl nodes. Our work provides a unified basis for understanding topological properties of the Mn$_3X$ family, which challenges previous experimental interpretations based on DFT band structures and predicts potentially higher anomalous Hall conductivity in Mn$_3$Ga under electron doping. This underscores the importance of a correlation-aware framework beyond DFT in understanding topological magnetic materials.