Study Of Anomalous Hall Effect In Co-based Spintronic Materials

With the rapid development of spintronics, the materials with strong spin-orbit coupling have been widely concerned. Co-based multilayers have been a good candidate for the further magnetic random access memory cell and magnetic sensor because of its strong spin-orbit coupling and tunable magnetic anisotropy. In the past decades, the study of the anomalous Hall effect (AHE) in Co-based multilayers has maken some progress. But some problems still need to make clear. For example, the complicated mechanisms of AHE and the weak AHE in Co-based multilayers limit the design of AHE-based devices. Therefore, further research on AHE in Co-based multilayers could help us make clear the mechanismS of AHE in Co-based multilayers and design new spintronics devices based on AHE. In this thesis, we study the AHE in [Co/Pt]n multilayers by magnetron sputtering and physical property measurement system. The mainly research results are as follow:We study the influence of defect concentration on the Hall sensitivity in MgO/[Co/Pt]3/MgO. The Hall sensitivity up to8363Ω/T was obtained in [Co/Pt]3multilayers by manipulating the defect concentration at oxide/metal interface, which is several times larger than that of the current best semiconductor Hall sensor. Our results show the decrease of defect concentration has important role in Hall senstitivity.AHE in [Co/Pt]3multilayers sandwiched by MgO/CoO hybrid layers is investigated. AHE in [Co/Pt]3multilayers sandwiched by MgO/CoO hybrid layers is67%larger than that in [Co/Pt]3multilayers sandwiched by MgO layers. Meawhile, magnetic perpendicular anisotropy is enhanced. The mircostructure results show the improved of crystallization of multilayers and modified interfacial structure play a cirtical role in the increment of AHE.We design an AHE material used in3D storage device and propose the concept of spin abacus. Artificial "Quantum Hall state" was successfully achieved in Co-based multilayers and NiO stack. The concept provides a promising approach for next generation high density, high speed nonvolatile3D storage technology.Effect of MgO/Co interface interface and Co/MgO interface on the spin dependent transport in perpendicular [Co/Pt]3multilayers is investigated. Our results show that the chemical state and electron structure are different due to the stacking order, which lead to different Hall behavior in [Co/Pt]3multilayers.We study the influence of different oxides on Hall angle in [Co/Pt]3multilayers. The giant Hall angle (5.1%) in [Co/Pt]n multilayers at room temperature is obtained in CoO/[Co/Pt]7/CoO. The research results make the Hall device directly compatible with CMOS technology, without amplifying circuit, leading to improve the integration of device. Our results show different oxides/metal interface will lead different electron scattering, which have important role in Hall angle. And the enhanced number of Co/Pt interface has a cirtical role in Hall behavior.