Resonant anomalous Hall effect in a ferromagnetic Weyl semimetal

Abstract

The anomalous Hall effect (AHE) has been widely studied and is well-known in ferromagnetic metals. It is usually investigated in the static regime with the magnetization at equilibrium. In this work, we study the AHE in the dynamic regime where the magnetization is resonantly excited. The microwave-induced ac current and magnetization precession both at GHz frequencies can cooperatively generate a dc voltage. In conventional ferromagnets, this effect, dubbed as resonant AHE (RAHE), is often overwhelmed by other effects such as spin pumping and spin rectification induced by anisotropic magnetoresistance. Here, we observe the RAHE in Co2MnGa, a ferromagnetic Weyl semimetal. In this material, the RAHE dominates over other effects, as observed in angle-dependent measurements. The RAHE in Co2MnGa is an order of magnitude larger than in Permalloy, a conventional ferromagnet. This enhancement is induced by the Berry curvature in the topological band structure of Co2MnGa. The large RAHE demonstrated in this work provides a viable methodology to convert microwave signals into dc voltages for telecommunication applications.