Magnetoelastic instabilities in kagome antiferromagnet Mn3-xGa

TL;DR

This study explores how varying composition in Mn3-xGa kagome antiferromagnets induces lattice, magnetic, and transport phenomena, revealing magnetoelastic coupling effects and topological transport property control.

Contribution

It demonstrates that composition controls magnetoelastic coupling and topological transport properties, unifying previous experimental findings in Mn3-xGa alloys.

Findings

Identified composition-dependent lattice responses, including zero thermal expansion and phase transitions.

Observed correlated magnetic and transport anomalies such as metamagnetic transitions and negative magnetoresistance.

Showed that Hall sign reversal stems from crystal-symmetry breaking, not magnetic reorientation.

Abstract

We present a systematic study of the structural, magnetic, and transport properties of hexagonal Mn3-xGa alloys, revealing a series of composition-controlled emergent phenomena. By tuning the Mn concentration, we uncover distinct lattice responses, including a zero thermal expansion-like volume compensation behavior in Mn-poor compositions and a magnetoelastic-driven, field-assisted structural phase transition in Mn-rich samples. These lattice instabilities are accompanied by correlated magnetic and transport anomalies, including metamagnetic transitions, negative magnetoresistance, and anomalous Hall sign reversal. First-principles calculations demonstrate that the Hall sign reversal originates from crystal-symmetry breaking rather than magnetic reorientation alone. Our results establish composition as the key control parameter governing magnetoelastic coupling in Mn3-xGa, providing a unified framework to tailor structural, magnetic, and topological transport properties in kagome antiferromagnets and reconcile previously disparate experimental observations.