The Standing Spin Wave In Permalloy Films

The LLG equation is a vital theory to describe the dynamic characteristics of magnetic materials, and can be used to describe the resonance phenomenon in ferromagnetic materials solely. However, when the Standing Spin Wave that is perpendicular to the plane of ferromagnetic metal films occurs, the exchange field arising from the disorder of the spin moments varies with the time and possesses the space curl. Based on the Maxwell equations, the curl of the magnetic field must be a current existing in the space, and a magnetic field changing with the time can generate an eddy electric field. So the exchange field would generate an oscillating current and an eddy current in the ferromagnetic metal films, and because of these currents, the transmission characteristics of microwave would be influent markedly.In this thesis, firstly, we predicted the existing of these currents according to the Maxwell equations. Then we adopted the spin rectification technology to detect the conductive current which conducted along the direction of the external field, since the distribution of currents in the ferromagnetic films was so complicate. Based on the data we acquired from experiments, this thesis found two robust proofs which can support our hypothesis:1. The lineshape of spin rectification signals generated by the Standing Spin Wave always shows as the Dispersion; by contrast, the spin rectification signals’ lineshape of ferromagnetic resonance is the mixture of Dispersion and Lorenz.2. The spatial symmetry relying on the external field of the spin rectification signals of the Standing Spin Wave is distinct from the Ferromagnetic Resonance.Based on these results, this thesis has adopted LLG equation and Maxwell equations to prove the existing of the current referred to above, adequately.Following this experiment, we designed another experiment detecting the Standing Spin Wave in the permalloy films using the ESR spectrometer. In contrast with the Ferromagnetic Resonance, when the Standing Spin Wave was excited in the permolly film, the distribution of microwave in the TE001 resonance cavity was changed drastically. This phenomenon arose from the eddy current in the plane of permolly films excited by the Standing Spin Wave. According to this result, it is clear that Standing Spin Wave in ferromagnetic metal films would excite two oscillating currents:one is a conductive current along the direction of the external field, and the other one is a eddy current in the plane of films.