Phase transitions associated with magnetic-field induced topological orbital momenta in a non-collinear antiferromagnet

TL;DR

This study reveals magnetic-field-induced phase transitions and topological orbital moments in a polycrystalline non-collinear antiferromagnet, expanding understanding of magnetic phases and potential spintronic applications.

Contribution

It demonstrates that magnetic phase transitions and topological orbital moments can be observed in polycrystalline materials, where anisotropy effects are canceled, highlighting exchange interactions as the controlling factor.

Findings

Resistivity tensor components change at low temperatures indicating magnetic phase transitions.

Transitions are associated with field-induced topological orbital moments.

Off-diagonal resistivity observed, suggesting new avenues for antiferromagnetic spintronics.

Abstract

Resistivity measurements are widely exploited to uncover electronic excitations and phase transitions in metallic solids. While single crystals are preferably studied to explore crystalline anisotropies, these usually cancel out in polycrystalline materials. Here we show that in polycrystalline Mn3Zn0.5Ge0.5N with non-collinear antiferromagnetic order, changes in the diagonal and, rather unexpected, off-diagonal components of the resistivity tensor occur at low temperatures indicating subtle transitions between magnetic phases of different symmetry. This is supported by neutron scattering and explained within a phenomenological model which suggests that the phase transitions in magnetic field are associated with field induced topological orbital momenta. The fact that we observe transitions between spin phases in a polycrystal, where effects of crystalline anisotropy are cancelled suggests that they are only controlled by exchange interactions. The observation of an off-diagonal resistivity extends the possibilities for realising antiferromagnetic spintronics with polycrystalline materials.