Research On The Anomalous Hall Effect And Measurements Of MnGa Thin Films

In recent years,the thin film with perpendicular magnetic anisotropy becomes one of the hotspots being studied by the domestic and foreign researchers.It is of great importance to search a material with perpendicular magnetic anisotropy;MnGa thin film has great potentiality due to its characteristic advantages such as uniaxial magnetic anisotropy,large spin polarization,low damping coefficient and controllable saturation magnetization.It can be applied in manufacturing spin transfer torque random access memory and perpendicular magnetic recording media.Anomalous Hall Effect is very significant and direct tool for investigating perpendicular magnetic thin film.Consequently,it is necessary to study the Anomalous Hall Effect of MnGa thin films.In this thesis,focusing on MnGa single layer thin film,a set of MnGa samples with various Mn concentration were prepared on MgO substrate by RF magnetron sputtering.The work was carried out basing on the Kondo Effect of MnGa thin films.Both Anomalous Hall Effect and Kondo Effect are closely linked to spin-orbit coupling and impurity spin;at low temperature,the Kondo Effect and electron weak anti-localization which may effect on the intrinsic Anomalous Hall Effect resistivity were discussed simultaneously,and the relationship between Anomalous Hall Effect and Kondo Effect were simply analyzed.Eventually,from the application point of view,the Anomalous Hall Effect of MnGa/Fe and MnGa/Fe?t?/Cr multilayers were examined preliminarily,and the corresponding results obtained in the experiment are analyzed and interpreted.What's more,the hardware and software development of Measurement system for the Anomalous Hall Effect was described in detail;the formula dealing with raw data was briefly derived;at the same time,the test system error was also analyzed and correction of system error was realized by software design.The research results indicate that?1?the Anomalous Hall Effect is obvious while annealed at 500?for 1 h,i.e.,MnGa thin films have the best the electrical and magnetic transport properties,which may be ascribed to this temperature which leads to small the grain size small and low surface roughness of MnGa thin films.?2?There exists the minimum temperature-dependent longitudinal resistivity.The longitudinal resistivity decreases monotonically with temperature cooling down from RT to Kondo temperature point?about 60 K?but increases when temperature further decreases from 60 K to 1.9 K.However,the change of Anomalous Hall Effect resistivity exactly opposes to that of longitudinal resistivity.?3?The Kondo Effect can weaken the Anomalous Hall Effect at low temperature.?4?Under the condition of sputtering parameter for MnGa multilayers in this article,the property of the MnGa multilayers deposited on Si/SiO₂ substrate is much better than that on MgO substrate.