Observation of structural distortion and topological Hall effect in noncollinear antiferromagnetic hexagonal Mn3Ga magnets

The structure, magnetism, and topological transport properties of noncollinear antiferromagnetic hexagonal Mn3Ga magnets have been investigated. Structural analyses reveal that as the temperature decreases, hexagonal Mn3Ga shows a Jahn–Teller-like distortion at T = 120 K. The distortion results in the anisotropy decreasing with decreasing temperature. Positive magnetoresistance is observed, and humps occur at low magnetic fields, which can be understood by breaking the ordered antiferromagnetic configuration by an external field and the spin-dependent scattering mechanism, respectively. In addition, a large topological Hall effect is observed in Mn3Ga, which originates from the noncollinear triangular magnetic configuration with slight distortion. The results are discussed in the context of coupling with noncollinear spin canting, lattice distortion, and topological transport.