Magnetization Dynamics Of Magnonphonon And Magnon-Magnon Coupling In Magnetic Hybrid Heterostructures

Spin waves?magnons?have shown great prospects in information processing and transmission,but the application is limited due to the low excitation efficiency and high dissipation intensity of magnons.At the same time,the traditional microwave devices are also facing the challenge of the miniaturization of chips.The sound waves?phonons?propagating on the single crystal substrate,show the advantages of low dissipation,short wavelength?typical wavelength is in the order of micrometer at GHz frequency?,and propagating in the medium,which is more suitable for communication and information processing.If the phonons are used as the carriers of information processing and transmission,a new generation of mobile communication chip with low-power,high-efficiency and miniaturized size will be realized.Therefore,the investigations of magnon-phonon and magnon-mganon coupling are very important for the spintronics and novel phononic devices.In the present work,we have investigated the magnon-phonon and magnon-mganon coupling in magnetic hybrid heterostructures.Firstly,we studied the phonon transmission in LiNbO₃ manipulated by the dynamic magnetization in a magnetic thin film,and we realized the phonon transport controlled by ferromagnetic resonance?FMR?;Secondly,we investigated the non-local magnon probe in coupled magnon system;Thirdly,we optimizated magnetoimpedance effect via magnetoelastic coupling effect and studied the magnetoimpedance effect in magnetic hybrid heterostructures.Details are provided below:?1?We have prepared the surface acoustic wave?SAW?devices,and the SAW harmonics proterties are measured using a vector network analyzer?VNA?.Firstly,two-dimensional image of SAW is observed by using magneto-optical Kerr effect?MOKE?depending on magnetoelastic coupling effect at room temperature in FeGa/LiNbO₃device,which provides a visible approach for investigation and application of SAW.Magnetoelastic coupling effect on magnetization process of FeGa film,via SAW induced stress field,are investigated.Secondly,the energy asorption during SAW dirven magnetization of Ni in Ni/LiNbO₃ device are studied.Thirdly,we tudied the phonon transmission in LiNbO₃ manipulated by the dynamic magnetization in a Ni thin film.It was observed that the phonons could be absorbed strongly through resonant magnon-phonon coupling,which was realized by optimizing the interfacial coupling between Ni and LiNbO₃.The line shapes of phonon transmission were further investigated considering the magnon-phonon interconversion in the elastically driven FMR process.Lastly,we studied resonant coupling of magnon-phonon which can be directly visualized by using micro focused Brillouin light scattering in the Ni/LiNbO₃hybrid heterostructures.?2?We investigtead the magnon-magnon coupling domainted by interface coupling in magnetic hybrid heterostructures.Fisrtly,the FMR property in the magnetic heterostructures,consisting of Fe nanowire arrays?FNWs?and Fe₂₅Ni₇₅ film,is investigated by using frequency sweep mode and field sweep mode.We found that the FNWs will dominate the static magnetic properties of nano-brush samples due to the large magnetizaiton.The FeNi film,on the other hand,will have domination on their dynamic magnetic properties due to the lager damping of FNWs.Secondly,we experimentally identify coherent spin pumping in the magnon-magnon hybrid modes of permalloy/yttrium iron garnet?Py/YIG/GGG?bilayers.The coupling is dominated by the exchange interaction at the interface of the magnetic bilayers,providing a new pathway to coherently transfer magnon excitations between two magnetic systems possessing distinctive properties:from conductor to insulator,from uniform to nonuniform mode and from high-damping to low-damping systems.Then we investigated the non-local magnons probe in this coupled magnon system device.We also measured the decay properties of spin wave mode of YIG by using micro focused Brillouin light scattering.?3?Fisrtly,the influence of cycle rapid cooling treatment on the giant magnetoimpedance?GMI?properties based on via magnetoelastic coupling effect in Co-based amorphous alloys was investigated.We found that internal thermoelastic stress leads to the changes of surface roughness,magnetic domain structures and saturation magnetization of the ribbons during different cycle processes.It was also found that the asymmetric GMI?AGMI?phenomenon occurred in the Co-based alloys with thermal cycle treatment after annealing,which can be regarded as a new method to get GMI-valve to improve GMI sensitivity.Secondly,based on the experiment results,a model in view of magnetostrictive energy is proposed to analyze the bluntness of the peak of GMI curve and the process of transverse permeability varying with the external field near zero-field in the Co-based amorphous ribbons,and all the experiment results have good agreements with our model.Thirdly,the FeCo or FeCoP film deposited on Fe_73.5Cu₁Nb₃Si_13.5B₉ amorphous ribbon constitute the magnetic sandwich structures,and the giant magnetoimpedance?GMI?properties of the structures have been investigated.A model of magnetic sandwich structure?F2\F1\F2?with three ferromagnetism layers is proposed to analyze the dependence of the impedance of sandwich structures on film thickness and permeability,and the numerical calculations have a good agreement with our experiment results.