Investigation Of Spin Dynamics In Magnetic Film And Spintronics Device

With the dramatically development of electronic information industry after the third industrial revolution,the electronic component is required to be miniaturization,large scale integration,and low energy consumption.However,the density of electronic component of integrated circuits increases slowly recent years,due to the lithography technology,the size of material,and the quantum tunneling effect for traditional electronic component based on semiconductor.Therefore,several novel electronic components utilizing various principle are widely studied,in which the spintronics device is the most remarkable area.The spintronics device could work in concert with the current electronic component based on semiconductor.Meantime,the spintronics device is low energy consumption,non-volatile,and highperformance,so the spintronics device and the film material are the heat area of research at present.This dissertation mainly studied spin dynamics by researching the spin-transfer torque oscillator and novel magnon valve by means of micromagnetic simulation and network analyzer.In addition,the large anisotropy of intrinsic damping constant is studied in the ultrathin Fe monocrystalline film,which may benefit designing new type spintronics device.To be specific,the main research content of this dissertation consists of three parts:First,the spin-transfer torque oscillator with the Dzyaloshinsky-Moriya interaction is studied by micromagnetic simulation.The frequency of spin-transfer torque oscillator decreases around 2 GHz by the influence of Dzyaloshinsky-Moriya interaction.Meantime,the power of spin-transfer torque oscillator decreases as well.More importantly,the directional spin wave is stimulated in the free layer and the direction of spin wave could be steadily modulated by the external magnetic field.Second,the magnon valve is fabricated with the structure of Fe/Ga As/Ni Fe.The influence of external microwave on magnon valve is studied by using vector network analyzer.The result shows that the magneto-impedance of the magnon valve increases up to 40% when applying an external 3.4 GHz microwave.In order to explain such an enhancement of magnetoimpedance,a proper theoretical model is proposed to describe the physical principle of this magnon valve.Third,the intrinsic damping constant of Fe film and Co Fe B film is studied by timeresolved magneto-optical Kerr effect.The large anisotropy of magnetic damping is found in the ultrathin Fe film.For the Fe film with thickness of 8 monolayers,the magnetic damping constant along 110 orientation increases by 66% compared with that along 110 orientation.In addition,the uniaxial magnetic damping is clearly correlated to the in-plane uniaxial anisotropy field of the Fe film.For Co Fe B film,the intrinsic damping constant is studied by applying external current and changing the thickness of the film.