Improvement of anomalous Hall effect of ferromagnetic thin films with perpendicular magnetization and its application to integrated non-volatile memory

在本研究中，观察到具有垂直磁各向异性的非常薄的薄膜的铁磁霍尔效应，旨在将其应用于非volatic存储单元。反常霍尔效应（AHE）和平面霍尔效应（PHE）代表双层介质中磁化的垂直分量和面内分量。由于AHE和PHE关于所施加的磁场H具有不同的对称性，因此很容易从测量的霍尔电压V_H中区分与M成比例的AHE分量和与M^2成比例的PHE分量。当外加磁场与膜面法线成一定角度时，观察到Co-Cr-Ta和Ni-Fe双层膜的霍尔电压。所观察到的V_H-H特性被视为PHE和AHE的霍尔电压输出之和。从这些特征可以很容易地确定垂直分量和面内分量，它们分别被认为是Co-Cr-Ta和Ni-Fe层的磁化过程。霍尔测量对于研究垂直磁记录系统中双层介质的磁化特性是有用的。此外，本文还提出了一种利用反常霍尔测量和VSM测量来评价倾斜磁场下垂直磁记录层中粒子间磁相互作用的新方法。这些结果对于本项目中提出的霍尔存储单元的设计是非常方便的。

In this research, a ferromagnetic Hall effect of very thin film with perpendicular magnetic anisotropy were observed aiming for their application to non-volatic memory cells. An anomalous Hall effect (AHE) and a planar Hall effect (PHE) represent a perpendicular component and an in-plane component of the magnetization in the double-layered media. Since AHE and PHE have different symmetries regarding to the applied magnetic field H, it is easy to distinguish the AHE component, which is proportional to M, and PHE component, which is proportional to M^2, from the measured Hall voltage V_H. The Hall voltage of the double-layered film composed of Co-Cr-Ta and Ni-Fe layers was observed when the magnetic field is applied at a certain angle from the normal to the film plane. The observed V_H-H characteristics are regarded as a sum of Hall voltage outputs of PHE and AHE. The perpendicular and the in-plane components, which are regarded as the magnetization process of Co-Cr-Ta and that of Ni-Fe layer, respectively, can be easily determined from these characteristics. The Hall measurement is useful to study the magnetization characteristics in the double-layered media in perpendicular magnetic recording system. Furthermore, A new method for evaluating magnetic interaction among the particles in perpendicular magnetic recording layers under canted magnetic field have been proposed using Anomalous Hall measurement and VSM measurement. These results were very convenient to design Hall memory cells proposed in this project.