The Spin-Hall Magnetoresistance In Composite Films Of Ta/Cr/YIG And Rh/CoFeB

Compared with the devices based on the charge property of electron,the power consumption in devices using electron spin to transfer information can be greatly reduced.Therefore,the electron spin can be a good information carrier.The research on spin-Hall magnetoresistance(SMR)reflects the ability of metal to generate spin current,so the SMR in composite films has attracted the attention of many research groupsIn this dissertation,we analyze the ability of metal to generate spin current by measuring the SMR in Ta/Cr/YIG and Rh/CoFeB composite films.The SMR ratio in Ta/Cr/YIG composite films is 4.2×10-4 at 100 K,which is an order of magnitude larger than that previously reported in Ta/YIG or Cr/YIG systems.The enhancement of SMR in the Ta/Cr/YIG is ascribed to the joint contribution of Ta and Cr,indicating the combination of Ta and Cr can be a good spin current generator.When the thickness of Cr increases to 3 nm and 6 nm,the sign of SMR in Ta/Cr/YIG changes from positive to negative at low temperature,which results from the spin-flop coupling between antiferromagnetic Cr and ferromagnetic YIG.In addition,the anomalous-Hall resistance(AHR)in Ta/Cr/YIG indicates that the Cr becomes ferromagnetic.The AHR linearly increases with the reciprocal of the Cr thickness,indicating the ferromagnetism originates from interfacial interaction between the Cr and YIG layersIn Rh/CoFeB system,the Rh thickness dependent SMR curves are measured And the spin-Hall angle ?SH=0.02858 and spin diffusion length ?N=3.38856 nm are obtained by fitting curves with formula,indicating the Rh has a strong ability to generate spin current.In addition,when the thickness of heavy metal Rh is fixed and thickness of CoFeB changes,the SMR ratio reaches a maximum when the thickness of CoFeB is about 1.5 nm,which is related to the shunting effect and spin diffusion length of CoFeB.The spin-Hall angle of Rh in this dissertation is obtained in this dissertation,and the SMR in Ta/Cr/YIG shows that the combination of metal layers may be a better spin current resource,which provides a certain reference for the choice of spin current generator.