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

在本研究项目中，利用磁阻(MR)测量方法研究了半导体氧化物(TiOx和SnOx)/铁磁多层膜的磁电性质。采用半导体材料作为CPP器件的非磁隔离层，其结电阻可以小于典型的由Al_2O_3层组成的TMR器件。认为降低CPP器件中的结电阻对读出的应用是非常重要的。硬盘的磁头。制备的多层膜由Subst/CoPt(10 Nm)/Co(2 Nm)/Sc(T Nm)/Co(4 Nm)/Sc(T)/Co(2 Nm)/CoPt(10 Nm)组成，其中Sc=TiOx或SnOx，t=4，8 nm。采用射频磁控溅射和直流磁控溅射的方法在玻璃衬底上制备了多层膜，并用光刻和Ar离子刻蚀的方法将其图案化成CPP器件结构。CPP输运的有效面积为5μm×5μm。从样品的磁阻(MR)测量结果来看，它是…的此外，还发现TiOx基多层膜的MR比(77K时为0.1%)远小于SnOx基多层膜的MR比(77K时为2.0%)。此外，基于TiOx的多层膜的MR分布在饱和行为上与其他多层膜完全不同。在TiOx基多层膜的MR曲线上观察到的大的饱和场比用VSM测得的MH曲线的饱和场大一个数量级，这表明由于Co和TiOx层之间的层间原子扩散，CPP的输运性质是由Co团簇的超顺磁性行为决定的。这种Co原子向TiOx层的层间扩散会抑制TiOx基多层膜的磁阻比。在SnOx基多层膜的MR曲线中没有观察到这种超顺磁性行为。这表明SnOx的加入抑制了铁磁性Co原子向半导体氧化层的扩散。当SnOx层厚度从4 nm增加到8 nm时，MR比率从2.1%下降到1.0%。认为这是由于自旋极化的电子在SnOx层中的散射引起的。较少

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