Rapid Characterizing Of The Dynamic Property Of Ferromagnetic Materials Using Spin Rectification

Spin rectification is an effect which transforms the electromagnetic wave into DC signals through magnetization precession. Since the DC signal strength has nothing to do with the volume generated by this effect, so that it has become a new generation method to study magnetization dynamics after cavity FMR and short-circuit microstrip line. Because of spin rectification only with a complex micro-nano device processing to achieve, thereby constraining its popularity in the dynamic research of magnetic materials. In this thesis, we have utilized the asymmetric electromagnetic environment to detect the rectified signal in the pure FM film sample, and develop a rapid characterizing method to study the dynamic performance of the pure FM film by this effect. Based on this work, we proposed to further improve the signal strength using FM/NM bilayer structure of the magnetic film. Introduction of NM, the magnetic layer can not only aggravate the asymmetry of electromagnetic environment, but also for the NM with large spin-orbit interaction, the spin current due to spin Hall effect would exert additional torque on FM to drive spin precession, improving the sensitivity of this method. The main conclusions are as follows:1) We propose a rapid characterizing approach based on spin rectification. When directly sending a rf current into a magnetic film, resonant dc voltages can be detected either along its longitudinal direction(parallel to the direction of current) or along its transverse direction(vertical current direction).As a standard sample, Fe/Ga As(010) single-crystal films with precise crystalline structure and magnetic parameters were used to study in detail to verify that the longitudinal signal comes from anisotropic magnetoresistance effect(AMR) and the transverse signal comes from abnormal hall effect(AHE). So, we can quickly and easily obtain the dynamic parameters of magnetic materials, such as effective demagnetization field, anisotropy field, the gyromagnetic ratio, intrinsic and extrinsic magnetic damping.2) Introduction of non-magnetic metal layer greatly increase signal strength of this method. We found that the reason why the pure magnetic metal film can be directly causes the rectified signal is the asymmetry of the electromagnetic environment, causing a non-uniform current distribution and generating a net magnetic field driven magnetization precession. In order to further improve the sensitivity of this method, we exacerbate the asymmetry of the electromagnetic environment by covering non-magnetic metal layer on the magnetic film. It was found that, the signal increased about one order of magnitude after covering a Cu layer compared to single-layer magnetic film; After covering the Pt layer, semaphore upgrade includes not only increased the contribution of asymmetry, but also the contribution of spin transfer torque(STT).