Spin Rectification Effect In Single Ferromagnetic Metal Films

Spin rectification (SR) makes the dynamic current to direct voltage by the local spin precession in ferromagnetic, which is the theoretical basis of electrically detected ferromagnetic resonance. In this thesis, we systematically introduce the mechanism of SR from theory and experiment. We find that not only the Anisotropic Magnetoresistance (AMR) could induce SR,but also Planar Hall Effect (PHE), Anomalous Hall effect (AHE) can also motivate the SR in lateral direction. Considering the vector of microwave, we make the angular dependent amplitude of voltage signal as the key to systematically research the characteristic of SR induced by different magnetoresistance mechanisms. Except systematically researching the mechanism of SR in single ferromagnetic metal films, we also put forward the universal method of SR, namely, angular dependent amplitude of SR voltage signal could be used to differentiate SR mechanism and spin driving torque.1) Systematically derive the theory about the spin rectification based on AMR, PHE, AHE (i.e., AMR rectification, PHE rectification, AHE rectification). The physical picture of three rectifications are built on solving the simultaneous equations of Generalized Ohm’s Law and LLG equation that used to describe dynamic magnetization. A time dependent resistance caused by dynamic magnetization could make the rf current into dc voltage. Based on these theory, we propose the method, angular dependent amplitude of voltage signal, to separate the mixed dc voltage signal caused by different physical effect and detect the magnetic field vector of microwave in material.2) Test and verify the AMR rectification, PHE rectification, AHE rectification by controlling the direction of microwave. In order to avoid the mixing of PHE rectification and AHE rectification, we choose Fe19Ni81 thin film with strong anisotropic magnetoresistance (AMR) effect to verify AMR rectification and PHE rectification. Instead, the Co90Zr10thin film has strong AHE effect, which make it to verify AHE rectification. A designer microwave devices is used to control the direction of rf magnetic field. The dependence of dc voltage on angle was study in different directions of rf magnetic field, which intuitively verify the theory of SR proposed by us.3) Propose the universal method of spin rectification:the angular dependent amplitude of SR voltage signal is the key to differentiate SR mechanisms and spin driving torque. Because of electromagnetic induction, SR exists universally in ferromagnetic conductors. At present How to separate the voltage signal from mixing signals is the difficult question in dynamic spintronics. By the theory and experiment confirmed with each other, the angular dependent amplitude of SR voltage signal is the most effective way.