Magnetic Transport And Dynamic Magnetic Properties Of Perovskite Oxide La_1-XSr_xMnO₃Films

The processing and transmission of information by spin current is an effective way to realize efficient energy storage and calculation,and the heterostructure composed of ferromagnetic layer / non-magnetic layer is the core of the integrated device to realize spin current generation and detection.Although the focus of research in the past decade has been on how to improve the conversion efficiency between spin current and charge current in non-magnetic layer,it has not achieved remarkable results so far.Therefore,in recent years,researchers have turned their attention to the magnetic layer,hoping to realize magnetic heterostructures with higher spin torque efficiency and new functions,such as subferromagnetic,antiferromagnetic and magnetic oxides,based on the rich and diverse electromagnetic properties of magnetic materials.Therefore,in recent years,researchers have turned their attention to magnetic layers,such as subferromagnetic,antiferromagnetic and magnetic oxides,hoping to creat magnetic heterostructures with higher spin torque efficiency and new functions based on the rich electromagnetic properties of magnetic materials.La_1-XSr_xMnO₃(LSMO)is a typical representative of ferromagnetic oxides.It is one of the most suitable magnetic oxides for showing spintronics related effects because of its 1)magnetic semi-metallic property with a spin polarization up to 100% and 2)the highest Curie temperature(above room temperature)of the perovskite ferromagnetic manganese oxides.This dissertation systematically studies the static and dynamic magnetic transport properties of LSMO single crystal epitaxial films with two typical components,La_0.67Sr_0.33MnO₃ and La_0.79Sr_0.21MnO₃.These works include:angle-dependent magnetoresistance in full-space,field-induced magnetoresistance in three highly symmetric directions,anomalous hall effect,spin rectification effect,kinetic parameter characterization and spin torque ferromagnetic resonance measurements in different temperature.The results show that the LSMO film has significant anisotropic magnetoresistance and anomalous Hall effect and small resonant damping,and is suitable as a magnetic layer in various spintronics devices,which lays a foundation for further exploring the potential of LSMO in spintronics related effects application.(1)LSMO single crystal films not only have significant anisotropic magnetoresistance and anomalous Hall effect,but also reach the maximum value at the transition temperature of metal insulators(equivalent to Curie temperature),showing similar characteristics to Pang magnetoresistance.(2)A single layer LSMO epitaxial single crystal film has current-induced torques,and its equivalent field has two components: one is along the normal direction of the film and the other is inside the film and perpendicular to the current.The two components do not change with temperature,but show strong frequency dependence.