  Non-trivial spin structures in itinerant magnets can give rise to topological
Hall effect (THE) due to the interacting local magnetic moments and conductive
electrons. While, in series of materials, THE has mostly been observed at low
temperatures far below room temperature (RT) limiting its potential
applications. Here, we report the anisotropic anomalous Hall effect (AHE) near
RT in LaMn2Ge2, a noncollinear ferromagnetic (FM) with Curie temperature TC=325
K. Large topological Hall resistivity of ~1.0 10-6 ohmcm in broad temperature
range (190 K <T< 300 K) is realized as field (H) parallel to the ab-plane (H //
ab) and current along c axis (I // c), in contrast to the conventional AHE for
H // c and I // ab. The emergence of THE is attributed to the spin chirality of
noncoplanar spin configurations stabilized by thermal fluctuation during spin
flop process. Moreover, the constructed temperature-field (H-T) phase diagrams
based on the isothermal topological Hall resistivity reveal a field-induced
transition from the noncoplanar spin configuration to polarized ferromagnetic
states. Our experimental realization of large THE near RT highlights LaMn2Ge2
as a promising system for functional applications in novel spintronic devices.
