Detecção elétrica da ressonância ferromagnética em filmes finos de NiFe/FeMn

Abstract

Devices based on effects that generate a dc voltage in ferromagnetic ressonance (FMR) condition are of great interest for broadband communication applications, since they allow the rectification of radio frequency signals by simple ferromagnetic materials. In general, FMR is achivied exposing the sample to a external magnetic field. However, depending on the excitation frequency, the static magnetic field required for the resonance is not low, which hinders technological applications. Exploring spin rectification and inverse spin Hall effects in exchange-biased samples it is possible to rectify radio frequency signals without an external applied magnetic field. Direct voltages of the order of V were obtained when NiFe/FeMn thin films were exposed to microwaves in a shorted microstrip line for a relatively broad frequency range. Connecting the films to a resistive load, the fraction of the incident radio frequency power converted into usable dc power is estimated. This procedure allows the efficiency measurement for applications in wireless power transfer.