Colossal Enhancement of Spin-Chirality-Related Hall Effect by Thermal Fluctuation

The effect of thermal fluctuation on the spin-chirality-induced anomalous Hall effect in itinerant magnets is studied theoretically. Considering a triangular-lattice model as an example, we find that a multiple-spin scattering induced by the fluctuating spins increases the Hall conductivity at a finite temperature. The temperature dependence of anomalous Hall conductivity is evaluated by a combination of an unbiased Monte Carlo simulation and perturbation theory. Our results show that the Hall conductivity can increase up to ${10}^3$ times the ground-state value; we discuss that this is a consequence of a skew-scattering contribution. This enhancement shows that the thermal fluctuation significantly affects the spin-chirality-related Hall effect. Our results are potentially relevant to the thermal enhancement of the anomalous Hall effect often seen in experiments.