Dissipationless Anomalous Hall Current in the Ferromagnetic Spinel CuCr 2 Se 4- x Br x

Abstract

In a ferromagnet, an applied electric field E invariably produces an anomalous Hall current J _H that flows perpendicular to the plane defined by E and M (the magnetization). For decades, the question of whether J _H is dissipationless (independent of the scattering rate) has been debated without experimental resolution. In the ferromagnetic spinel CuCr ₂ Se _{4– x} Br _x , the resistivity ρ (at low temperature) may be increased by several decades by varying x (Br) without degrading M. We show that J _H /E (normalized per carrier, at 5 kelvin) remains unchanged throughout. In addition to confirming the dissipationless nature of J _H , our finding has implications for the generation and study of spin-Hall currents in bulk samples.