Large topological Hall effect near room temperature in noncollinear ferromagnet LaMn2Ge2 single crystal

TL;DR

This study reports a large topological Hall effect near room temperature in LaMn2Ge2, a noncollinear ferromagnet, due to noncoplanar spin configurations, with potential implications for spintronic applications.

Contribution

The paper demonstrates the observation of a significant topological Hall effect near room temperature in LaMn2Ge2, a noncollinear ferromagnet, highlighting its potential for spintronic devices.

Findings

Large topological Hall resistivity (~1.0 10^-6 ohm·cm) observed between 190 K and 300 K.

The topological Hall effect is linked to noncoplanar spin configurations stabilized by thermal fluctuations.

Field-induced transition from noncoplanar to polarized ferromagnetic states identified in phase diagrams.

Abstract

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.