Generation And Measurement Of Spin Current In Non-magnetic/magnetic Insulators

With the development of science and technology,people demand more and more high memory density,traditional semiconductor devices are fronted with severe problems such as heat dissipation,and Moore's law is no longer applicable.The traditional semiconductor device only uses the charge property of the electron to transmit and process information,but does not use its spin property.Spintronics uses the spin property of the electron to transmit and process information.It is expected to solve the above problems and has broad research prospects and application value.The generation,transmission and detection of spin current is always the core of spintronics.In this paper,spin current is generated in non-magnetic/magnetic heterostructure in different ways,and the detection of spin current is realized by inverse spin hall effect?ISHE?.A series of important research results have been achieved.In the first chapter,we introduce the background and current status of ISHE research,as well as various ways of generating spin current,such as spin seebeck effect?SSE?,spin pumping and photo spin voltaic effect?PSVE?,and summarize the characteristics of different spin detection materials.The second chapter introduces the preparation method of the sample and the experimental equipment.In chapter three,the generation,transmission and detection of spin current in ITO/YIG are studied by means of spin pump effect and spin seebeck effect.In the spin pump experiment,ISHE analysis of ITO before and after annealing found that the appropriate annealing process can significantly increase interfacial spin mixing conductance and spin hall angle of ITO/YIG,which provides an important research idea for oxide as spin detection layer.In the spin seebeck effect experiment,we did not observe the inverse spin hall effect,which may be caused by too little interfacial temperature difference due to the almost identical thermal conductivity of ITO and YIG or the particularity of ITO/YIG interface structure,or by the negative temperature coefficient existing in the interfacial spin mixing conductance.In this regard,we propose possible solutions.In chapter four,the photo spin voltaic effect in Pd/YIG and Pt/YIG is mainly studied.It is found that under illumination,the V-H curve not only contains the photo spin voltage signal,but also exists a linear signal related to magnetic field and light intensity gradient.The photo spin voltage,linear signal and the relationship between them are studied in detail by changing the illumination conditions of the sample.We found that the linear signal can be powered by light-induced carrier migration in the direction of sample length.By changing the relative light intensity on both sides of the sample bar,the size of the linear signal can be adjusted.In addition,by changing the thickness of Pd layer,the magnitude of photo spin voltage can be changed on a large scale,which means that in PSVE,better spin detection effect can be obtained by adjusting the thickness of spin detection layer.In chapter five,we investigated the ISHE of three samples of Cu_0.97Bi_0.03?15nm?/YIG,Cu?15 nm?/YIG and Cu_0.95Bi_0.05?15 nm?/YIG,and we observed the inverse spin hall effect voltage of different sizes in three samples at room temperature.We found that the V_ISHEof Cu_0.97Bi_0.03?15 nm?/YIG is significantly greater than Cu?15nm?/YIG,which due to the increase of CuBi spin hall angle for Cu_0.97Bi_0.03 as a result of extrinsic scattering from Bi atoms.This means that the spin hall angle and inverse spin hall effect voltage of CuBi alloy can be enhanced by doping appropriate Bi atoms in Cu material.Finally,we summarize the whole paper and look forward to the future research.