Investigating temperature and magnetic field-dependent magnetic structures of square-net lattice compound LaMn2Ge2 by Single Crystal Neutron Diffraction

Magnetic topological insulators provide an important platform for realizing several exotic topological properties, such as anomalous Hall effect, anomalous Nernst effect, and topological Hall effect (THE), owing to the interplay between topology and magnetism. Antiferromagnetic (AFM) materials exhibit THE due to the presence of nontrivial spin structures. LaMn2Ge2 crystallizes in a tetragonal structure (I4/mmm) and exhibits ferromagnetic ordering at 325 K. We observed a large TH resistivity of ~4.5 μΩ-cm at room temperature. From magnetic studies, it is predicted that the large THE can be attributed to the noncollinear spin structure (conical) under applied magnetic fields. Therefore, a knowledge of the temperature and magnetic field dependent magnetic structures of LaMn2Ge2 by neutron diffraction is imperative to understand the origin of large TH resistivity. In addition, we observed large anomalous Hall conductivity due to the intrinsic Berry curvature contribution near to the Fermi level. These promising results suggest the possibility of spintronic devices based on antiferromagnets with tailored noncoplanar spin configurations.