Rare Earth Modification Of Yttrium Iron Garnet Film And Application Of Spin Wave Sensor

Yttrium iron garnet?YIG? film is an ideal carrier for the long-distance propagation of spin waves,which determines the properties of spin wave propagation.There have been many reports on the magnetization dynamics of YIG films at room temperature.However,the magnetization dynamics spin wave characteristics of rare earth doped YIG films at low temperatures are relatively few,and rare earth substituted YIG films usually have novel magnetization dynamics,so this study is very meaningful.In this paper,the magnetization dynamics of YIG thin films grown by rare earth doping and heterojunction prepared by magnetron sputtering at variable temperature and room temperature are studied.The advantages of YIG thin films are combined to design and produce a magnetic vibrator sensor with simple structure,low cost and high sensitivity.Our main tasks as follows:In the first part,the magnetization dynamics of yttrium?La?substituted YIG single crystal film grown by liquid phase epitaxy at variable temperature is systematically studied.First,a La:YIG single crystal thin film was grown on a yttrium gallium garnet(Gd₃Ga₅O₁₂)substrate by a liquid phase epitaxy.Then,the FMR spectrum of the La:YIG film was measured at different temperatures?55-300K?.Experiments show that the spin wave mode of La:YIG film increases with the increase of temperature,which indicates that the phonon can generate additional spin wave mode;When the temperature increases from 55K to 300K,the FMR line with??35?H?of La:YIG film has changed significantly;The nonlinear behavior at low temperature indicates that lanthanum is a slow relaxation element;The Gilbert damping factor of the La:YIG film is derived from the scattering of magnon-magnet and magnon-phonon,which can be used to construct a phonon-tuned spin wave device.In the second part,the modification of the formation of heterojunction by growing rare earth germanium?Dy?on YIG film by magnetron is introduced,and the magnetization dynamics of YIG/Dy heterojunction system at rom temperature is studied.Four groups of rare earth Dy layers with thicknesses of 10nm,20nm,40nm and60nm were grown on pure YIG substrates by DC magnetron sputtering.Annealing it to achieve Dy diffusion doping of the YIG surface.Experiments has shown that the modification of the magnetization dynamics of the YIG/Dy heterojunction is significant compared to the pure YIG film.As the thickness of Dy increases,the FMR of the YIG/Dy system increases,the Gilbert damping factor increases,the magneto-optical Kerr signal increases and it has an effect on the amplitude of the spin wave.In the third part,the magnetic vibrator sensor based on YIG film is designed and fabricated.Firstly,the fixture and microstrip antenna are designed by Proe and HFSS software respectively.Secondly,we lithography and etch the YIG film with a size of10×10mm² to obtain the core components of the sensor.Finally,we tested the parameters of the spin wave sensor and found the relationship between amplitude,frequency shift and concentration and humidity.The detection of the concentration of ferroferric oxide nanoparticles and the environmental humidity are realized.It is proved that the spin wave sensor realized in this study has the characteristics of simple structure,low cost and high sensitivity and can be applied to sensing and detection of magnetic nanoparticle concentration and environmental humidity.