APPLICATION OF SPIN-DEPENDENT TRANSPORT IN HYBRID SUPERLATTICE TO FUNCTIONAL DEVICES

在这项研究项目中，磁性和电性能的连续氧化物（TiOx和SnOx）/铁磁体多层膜的磁阻（MR）测量在CPP的几何形状进行了研究。用半导体材料作为CPP器件的非磁性隔离层，可以使结电阻小于典型的由Al_2O_3层组成的TMR器件的结电阻。降低CPP器件的结电阻对于读出的应用是非常重要的。硬盘的头。制备的多层膜由以下组分组成：CoPt（10 nm）/Co（2 nm）/SC（t nm）/Co（4 nm）/SC（t）/Co（2 nm）/CoPt（10 nm），其中SC=TiOx或SnOx，t= 4.8 nm。这些多层膜是用射频和直流磁控溅射法在玻璃衬底上制备的，用光刻和氩离子刻蚀的方法制作成CPP器件结构，CPP器件的传输有效面积为5 μm×5 μm。根据这些样品的磁电阻（MR）测量， 关于我们 发现TiOx基多层膜的MR比（在77 K时为0.1%）远小于SnOx基多层膜的MR比（在77 K时为2.0%）。此外，基于TiO x的多层膜的MR轮廓在饱和行为方面与另一种多层膜完全不同。在TiOx基多层膜的MR曲线中观察到的大饱和场比用VSM测量的MH曲线大一个数量级。这表明CPP输运性质由Co团簇的超顺磁性行为主导，这是由于Co和TiOx层之间的层间原子扩散。Co原子到TiOx层中的这种层间扩散将抑制基于TiOx的多层的MR比。这种超顺磁性行为在SnOx基多层膜的MR曲线中没有观察到。这表明，铁磁Co原子扩散到连续氧化物层中被使用SnOx抑制。随着SnOx层厚度从4 nm增加到8 nm，MR比率从2.1%降低到1.0%。据认为，这种下降是由于自旋极化电子在SnOx层中的散射引起的。少

In this research project, magnetic and electric properties of semiconductive-oxide (TiOx and SnOx)/ferromagnet multilayers were investigated by magnetoresistance (MR) measurements in a CPP geometry. By using semiconducting materials as a non-magnetic separating layer of a CPP device, the junction resistance can be smaller than that of typical TMR devices consisting of Al_2O_3 layer. It is considered that the lowering of the junction resistance in a CPP device is much important for the application of a readout. head of a hard disk. The prepared multilayers consisting of subst./CoPt (10 nm)/Co (2 nm)/SC (t nm)/Co (4 nm)/SC (t)/Co (2 nm)/CoPt (10 nm) where SC=TiOx or SnOx, t=4, 8 nm. These multilayers were prepared by rf- and dc-magnetron sputtering on a glass substrate at nominal temperature and patterned into CPP device structure by photo-lithography and Ar ion milling.The active area for the CPP transport was 5 μm×5 μm. From the magnetoresistance (MR) measurements of these samples, it … More was found that the MR ratio for the TiOx-based multilayer (0.1 % at 77 K) was much smaller than that for the SnOx-based one (2.0 % at 77 K). Furthermore, the MR profile of the TiOx-based multilarer was totally different from another one in the saturation behavior. The large saturation field observed in the MR curve of the TiOx-based multilayer was an order of larger than that for the MH curve measured with VSM.This indicates that the CPP transport property is dominated by the super-paramagnetic behavior of the Co cluster due to the interlayer atom diffusion between Co and TiOx layers. This interlayer diffusion of Co atoms into TiOx layer would suppress the MR ratio of the TiOx-based multilayer. This super-paramagnetic behavior was not observed in the MR curve of SnOx-based multilayer. This suggests that the diffusion of the ferromagnetic Co atoms into semiconductive-oxide layer was restrained by using SnOx. The MR ratio was decreased from 2.1 % to 1.0 % as increasing the SnOx layer thickness from 4 nm to 8 nm. It is considered that the decrease is caused by the scattering of the spin-polarized electron in SnOx layer. Less