| In order to realize on-chip integration and microwave signal direct processing for the next generation communication system?5G/6G?,the research on spin wave thin film wafer,spin wave on-chip integration device and spin wave transmission properties and spin rectification effect has become a hot topic.Based on the National Key Research and Development Plan,we explored the method of liquid phase epitaxy growth technology of ultra-low loss magnetic garnet films,designd and preparaed magnetic insulator/metal spin heterojunction,invented detect/receive microstrip antennas based spin wave transmission devices,explored the inverse spin Hall effect,set the ferromagnetic resonance linewidth test equipment,inverse spin hall effect test system,spin wave test system and found a few new spin wave effect.Studies are also carried out on optimization the sub-micron to nanoscale YIG film epitaxial growth technology,improving the ultra-low loss of magnetic thin film ferromagnetic resonance measurement technology,discussing the spin wave excitation/detection antenna technology for volume spinwave,and fabricating low loss thin film with large perpendicular magnetic anisotropy.The details are as follows:1)In order to achieve low loss materials and device miniaturization,we first studied the preparation of submicron single crystal YIG films,and prepared pure YIG and La:YIG films with thickness of 100 nm-1000 nm using liquid phase epitaxy technology.Some important conclusions are given by comparing thickness-dependent magnetostatic properties:?1?The high quality of pure YIG film causes the interface stress-induced anisotropy,which results in the change of magnetostatic properties.?2?The lattice of La:YIG film is slightly larger than that of pure YIG film,which is basically consistent with the lattice of GGG.There is no interfacial stress-induced anisotropy.?3?The Gilbert damping factor of pure YIG film mainly depends on film thickness,and the anisotropy has a relatively minor role,but there is an associated formant in ferromagnetic resonance spectrum.Aiming at the pattern requirements of YIG film,we studied the etching technology of YIG film,and gave the etching characteristics of concentrated phosphoric acid and the etching rates of phosphoric acid with different concentrations.2)For the ferromagnetic resonance test of YIG thin film,we carried out technological improvement.For the micron?<1?m?and ultra-thick?>10?m?YIG thin film,the eigen YIG FMR linewidth was measured by the technique of suppressing the edge field intensity of the waveguide.Optimization of the test results,according to the different measuring materials,the applicability and compatibility of ferromagnetic resonance test fixture requirements.Based on the ferromagnetic resonance test equipment,we built the SP-ISHE test system,which can be used for the spin wave detection and spin pump/inverse spin hall effect research of the electrical method.On the basis of this equipment,we study the characteristics of power-dependent inverse spin hall voltage,find the linear relationship between the resonant peak envelope area and the input power,and propose a microwave power detection technology based on the resonant peak film area,which provides a potential method for the practical use of spin rectifier devices.3)In order to realize the fabrication and testing of spin wave devices,we simulated the short-circuit coplanar waveguide excitation detection antenna,and compared with the coplanar waveguide antenna.A rotatable testing equipment for spin wave testing was built.Finally,we chose the short-circuit coplanar waveguide as the test antenna for the following reasons:?1?The short-circuit coplanar waveguide is easy to prepare,the area from the excitation end to the probe is large,and the bending structure can be avoided.The impedance matching problem is greatly alleviated compared with the coplanar waveguide.?2?The excitation area is a single-wire structure,and there will be no difficulty in stripping the three-wire structure,especially when the metal thickness is relatively thick;?3?The short-circuit coplanar waveguide can also selectively adjust the excitation wave vector through structural adjustment;?4?Short circuit coplanar waveguide does not need to narrow the coplanar waveguide signal line gradient section,the antenna area can be reduced,which is conducive to device miniaturization.4)Using the short-circuit coplanar waveguide,the anisotropic spin wave propagation of YIG thin film was studied,including the spin wave propagation of YIG thin film with in-plane anisotropic?100?crystal phase and?111?crystal phase under the multi-angle magnetic field.The spin wave propagation characteristics of YIG thin film and YIG/magnetic metal film heterojunction were compared.5)In order to solve the problem of large magnetization field and large magnetic loss of films,we prepared and studied low-loss spin wave waveguide materials with large magnetic anisotropy and induced magnetic anisotropy of garnet films by two methods.The first method is to induce anisotropy in YIG by epitaxial growth of stress layer on the surface of YIG film with a thickness of 110 nm.?1?Similar to most studies,the anisotropy induced by interfacial stress can only be maintained within a relatively thin thickness,and the stress will lead to a large Gilbert damping and a significant increase in the ferromagnetic line width;?2?By stress induction and stress relaxation,we can obtain multiple formant of ferromagnetic resonance,and different formant have great difference.?3?The spin spectrum of the magnetic bilayer presents a dipole gap caused by anomalous dispersion in the nonlinear interaction,and the comb spectrum spacing is 3.24 MHz.The second method is to prepare YBLCIG films by means of lattice constant control and saturation magnetization minish.The YBLCIG films have the following characteristics:?1?The saturation magnetization of the film is 702 Oe,the anisotropic field is 1862 Oe,and the surface saturation field is 337.8 Oe.?2?The pole diagram related to the coercive force Angle of the film shows a butterfly shape,while the saturation field is fusiform.?3?The film has excellent dynamic magnetization characteristics,with an external width of2 Oe/4 GHz,an OOP Gilbert damping is 2.46×10-3,group velocity of 2.25 km/s and attenuation length of 115 m.The film has an extremely low magnetic domain resonance linewidth.The domain width is about 1?m in demagnetization state. |
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