Magnetism and Magnetotransport in the Kagome Antiferromagnet $\text{Mn}_3\text{Ge}$

TL;DR

This study investigates the temperature-dependent magnetic and transport properties of the Kagome antiferromagnet Mn3Ge, revealing a chiral magnetic order below the Néel temperature and its impact on Weyl nodes and magnetotransport phenomena.

Contribution

The paper combines simulations and theoretical analysis to demonstrate the presence of multiple Weyl nodes and their influence on magnetotransport signatures in Mn3Ge, highlighting effects of magnetic chirality.

Findings

Long-range chiral order appears below T_N.

Multiple Weyl nodes contribute to magnetotransport.

Magnetic chirality affects LMC and PHC periodicity.

Abstract

We perform classical Monte Carlo and stochastic Landau-Lifshitz-Gilbert simulations to study temperature dependent magnetism of Kagome antiferromagnet (AFM) Weyl metal $\text{Mn}_3\text{Ge}$ and find that a long range chiral order sets in at a transition temperature well below the N{\'e}el temperature ($T_N$). Based on the crystalline symmetries, imposed by the chiral magnetic order, we argue for the presence of multiple iso-energetic Weyl nodes (nodes that are at same energy and with congruent Fermi surface around them) near chemical potential. Using the semi-classical Boltzmann equations, we show that the combined contribution to the net longitudinal magnetoconductance (LMC) and the planar Hall conductance (PHC) from tilted Weyl nodes can lead to signatures, qualitatively distinct from that of a single pair of Weyl nodes. In particular, we show that magnetic orders with different chiralities can give rise to different periods in LMC and PHC as a function of the in-plane magnetic field direction. This is ultimately related to differences in the symmetry-imposed constraints on the Weyl nodes.