Fabrication Of Ferimagnetic Insulator And Its Inverse Spin Hall Effect

In the past few years,the research based on electronic charge properties in traditional microelectronics has made great achievements.However,with the development of technology,the power consumption and integration of traditional electronic devices make it unable to meet people's demands.Gradually,another property of electron——spin,has become the focus of people's attention and spintronics has become an important branch of physics.Nowadays,people have mastered the technologies of spin current's generation,transmission and detection.On this basis,the spintronic devices developed are also expected to replace traditional microelectronic devices and play the most important role in our lives,leading information technology trend.Among them,for pure spin current,its generation,detection and utilization have always been the center of spintronics research.Compared to spin-polarized current,pure spin current has the unique property,which uses a minimum of charge carriers to transfer large amounts of angular momentum,resulting in less Joule heat.Spin Hall effect(SHE),lateral spin valve,spin pumping(SP),and spin Seebeck effect(SSE)etc are commonly used to generate pure spin currents.As a quasi-particle of a low-energy excited state in a ferromagnet,a magnon is a quantized carrier of angular momentum,and obeys boson behavior.In the ferromagnetic insulator,the movement of information can be carried out by the movement of the magnons with the spin angular momentum,and the influence of the Joule heat due to the movement of the conduction electrons can be avoided,thereby the power consumption of the device is greatly reduced.Therefore,it is an attractive method to generate pure spin current through some mechanism in ferromagnetic insulators.For the detection of spin currents,the development of heavy metals(such as Pt,W and Ta)with strong spin-orbit coupling(SOC)rather than typical high-Z paramagnets has become a trend in spintronics research.The inverse spin Hall effect in ferromagnetic metals is another means of effectively detecting spin currents.One work of this thesis is the sintering of ferrimagnetic insulator TmIG targets,as well as the performance characterization of targets and growth films.We chose the nitric acid fusion sintering method instead of the traditional solid phase reaction sintering process to fire the target,solving the problem of non-target material formation resulting from insufficient raw material fusion.We successfully sintered the high purity TmIG cylindrical target with diameter of two inchesand saturation magnetization of 15.4 emu/g.We used XRD to test the performance of the target powder.The result shows that the target composition is TmIG polycrystal.On this basis,we obtained TmIG films by magnetron sputtering teclhnology using our home-made target.The AGM measurement results proved that the TmIG films had perpendicular anisotropy,and the saturation magnetization per unit volume was 84.96 emu/cm3.Another work in this thesis is to observe the magnetization direction-dependent ISHE in ferromagnetic metals by spin Seebeck measurements in yttrium iron garnet(YIG)/Cu/IrMn/NiFe multilayer structures.Through the exchange bias between the NiFe and the IrMn,the magnetization direction(MYIG)in the YIG film can be rotated relative to the magnetization direction(MNiFe)of NiFe layer under a small external applied field.By observing the Inverse Spin Hall Effect(ISHE)voltage in the NiFe layer which depending on the magnetization direction,it is found that the spin Seebeck voltage when ?s and MYIG are parallel to each other is about 30%higher than that when as and MYIG are perpendicular to each other.