Experimental Setup Of The Brillouin Light Scattering Apparatus And Dynamics Of Magnons In Magnetic Film

Traditional microelectronics have always tended to study the charge of electron,and use electric field to control charge in order to realize the processing and transmission of information.However,spin,as another an important intrinsic property of electrons,has not been paid enough attention.Nowadays,with the continuous development of science and technology,the size of electronic devices is getting smaller and smaller.The contradiction between integration level and energy consumption is becoming more and more prominent in traditional integrated circuits,so people begin to turn their attention to spin property of electron.Through the processing of the amplitude and phase of the spin wave may provide a new low power signal processing and computing scheme.Thus,the study of spin in microcosmic system is rising gradually.Spintronics as a discipline that studies the generation transmission and control of spin current also emerge as the times require.Nowadays,spintronics has become a popular discipline in today's science field.spin-electronic devices is also promising to replace microelectronic devices and lead the new trend of information technology.Similar to the phonons in the crystal material,the spin wave is a description of the collective behavior of the spin low excitation state in the magnetic ordered system and its quantization unit is called the magnon.The dispersion relation of the magnon is influenced by the material parameters such as exchange interaction,magnetic anisotropy and saturation magnetization.Unlike phonons,the characteristic of the spin wave is that the direction of its propagation is influenced by the direction of magnetization.Brillouin light scattering(BLS)is a kind of inelastic scattering caused by photon-magnon interaction in materials.It is an effective way to understand the properties of materials by measuring inelastic scattering light.The high power laser is directly focused on the sample,and then the frequency difference between the scattered light and the incident light is analyzed.Its advantage is that it can directly obtain the wave vector and energy of the magnon,and can realize flexible measurement of the multi-degree freedom,broadband frequency resolution and local spatial resolution.The high precision frequency resolution is realized mainly by a tandem Fabry-Perot interferometer(TFP),and the local spatial resolution can be realized by controlling the size of the spot in 30 to 40 ?m by the high magnification lens.Using BLS method,we can study the gas,liquid and solids,such as using non-contact means to measure the phonon properties in liquid or organic materials.In spintronics,the BLS method is widely used to measure the properties of the spin wave,especially the spin wave frequency and dispersion relation.After decades of development,the BLS technology can be divided into conventional backward scattering,conventional forward scattering,spatially resolved micro-BLS and time-resolved BLS.The BLS system establishment is one of the works of this thesis.Based on the tandem Fabry-Perot interferometer,we designed and set up the optical path system according to our experimental requirement.We debugged the interferometer and micro optical system,so that it can meet the demand of our experiments.Another important work of this thesis is to measure the magnons(spin wave)in the magnetic film by Brillouin light scattering apparatus.This method is different from the ways people utilized before such as microwave measurements,because it detects the frequency and intensity of local magnons with specific wavevectors and dispersion relations directly via the spectra of scattering light instead of average data from the whole film.The investigations are made in room temperature using a 150mw polarized 532nm solid laser as light source,a 150mm lens to both focus the incident light and collect the scattering light beam,and a well-designed TFP to make the measurement of the broad spectral features of the magnon spectra possible.We observed magnetostatic surface waves(MSSW)(also called Damon-Eshbach(DE)spin waves)in variation of the magnitude of the applied magnetic field in samples of different structures.In consideration of the fact that samples we used are opaque,backward scattering technique is used,which means the reflected light goes back the way it comes is sent to the interferometer to be analyzed.