Spin Diffusion Length Of Nonmagnetic Films Modulated By Rare Earth

Spintronics has always been an important part of magnetic research,in which the most basic research object is the magnetic film with thickness in nanoscale.The relaxation speed of the magnetic film material during the procession magnetizations is determined by its magnetodynamic damping,which plays a key role in the magnetic storage and the reading speed of spintronic devices.As an essential technique to study dynamic properties of ferromagnetic films,ferromagnetic resonance?FMR?has received tremendous attention because of its high sensitivity and operability.In this paper,the spin pumping effect of ferromagnetic/nonmagnetic?FM/NM?double layer membrane structure is systematically studied by FMR.The spin orbit coupling of the nonmagnetic layer is increased by doping the rare earth?RE?Nd into NM layer.The angle dependence and frequency dependence of the resonance field and line width of the sample are measured.As a result,the modulation of the magnetodynamic damping is realized,and the spin diffusion length of the non magnetic layer and the spin mixing conductance of the FM/NM interface are discussed.The main results are as follows:1.Spin pumping research of Nd as a non-magnetic metal in ferromagnetic thin film?NiFe?/nonmagnetic?Nd?hetero-junctionPermalloy(Ni₈₀Fe₂₀)is an excellent soft magnetic material,except for its relatively low magnetodynamic damping,which results in a longer switching time and can hardly be used in spintronic devices.Spin pumping is an efficient method to modulate the magnetodynamic damping of ferromagnetic materials.It happens in the interface of a FM/NM system which will not destroy the magnetism of FM layer.Commonly the strength of spin pumping effect is decided by the spin-obit coupling of NM layer.Nd is a typical light RE metal with a strong spin orbit interaction,but its electronic structure is different from the commonly used heavy metal Pt.Does the rare earth Nd also have the ability to enhance the spin pumping effect of the FM/NM system and further modulate the magnetodynamic damping of the NiFe just like Pt?The study shows that the rare-earth layer Nd increases the spin pumping effect of the NiFe/Nd double layer film,and improves the Gilbert damping constant?of Permalloy,which is 0.0244 higher than that of NiFe/Pt,expanding the application of Permalloy in spintronic devices.2.Rare earth Nd doped Cu as a nonmagnetic layer to control spin pumping in FM/NM system.Copper is one of the most commonly used nonmagnetic materials in spin valve structure,however,its spin orbit coupling is too weak to arouse an obvious spin pumping effect in FM/Cu system,which results in a relatively tiny modulation effect of magnetodynamic damping.If doping rare earth Nd into Cu,is it possible to effectively manipulate the magnetodynamic damping of the adjacent FM?The study shows that with the increase of Nd doping content,the spin diffusion length of the non magnetic layer Cu-Nd decreases obviously,the interface mixing conductance and the damping factor are obviously increased.It is demonstrated that the spin orbit coupling of the nonmagnetic layer and the interface of the FM/NM system are modified,which play regulatory roles in the spin pumping.