Universal negative magnetoresistance in antiferromagnetic metals caused by symmetry breaking of electron wave functions

TL;DR

This paper proposes a new theoretical explanation for the negative magnetoresistance observed in antiferromagnetic metals, attributing it to symmetry breaking of electron wave functions, which aligns with experimental findings.

Contribution

It introduces a novel intrinsic mechanism based on T2 symmetry violation that explains negative magnetoresistance in AFM metals, filling a gap in theoretical understanding.

Findings

The mechanism is nearly isotropic to field and current directions.

Theoretical results qualitatively match experimental data across various materials.

The effect is significant in layered AFM-ordered semimetals.

Abstract

Layered van der Waals crystals of topologically non-trivial and trivial semimetals with antiferromagnetic (AFM) ordering of magnetic sublattice are known to exhibit a negative magnetoresistance that is well correlated with AFM magnetization changes in a magnetic field. This effect is reported in several experimental studies with EuFe2As2, EuSn2As2, EuSn2P2, etc., where the resistance decreases quadratically with field by about 5% up to the spin-polarization field. Although this effect is well documented experimentally, its theoretical explanation is missing up to date. Here, we propose a theoretical mechanism describing the observed magnetoresistance that is inherent in AFM metals and is based on violation the binary T2 symmetry. It is almost isotropic to the field and current directions, contrary to the known mechanisms such as giant magnetoresistance and chiral anomaly. The proposed intrinsic mechanism of magnetoresistance is strong in a wide class of the layered AFM-ordered semimetals. The theoretically calculated magnetoresistance is qualitatively consistent with experimental data for crystals of various composition.