2000 Fiscal Year Final Research Report Summary
APPLICATION OF SPIN-DEPENDENT TRANSPORT IN HYBRID SUPERLATTICE TO FUNCTIONAL DEVICES
| Project/Area Number |
10450139
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B).
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
電子デバイス・機器工学
|
|---|
| Research Institution | KYUSYU UNIVERSITY |
|---|
Principal Investigator |
MATSUYAMA Kimihide KYUSYU UNIVERSITY, Grad. School of Inform.Sci.and Elec.Eng., Prof., 大学院・システム情報科学研究院, 教授 (80165919)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
NOZAKI Yukio KYUSYU UNIVERSITY, Grad.School of Inform.Sci.and Elec.Eng., Res.Ass., 大学院・システム情報科学研究院, 助手 (30304760)
NAKASHI Kenichi KYUSYU UNIVERSITY, Grad.School of Inform.Sci.and Elec.Eng., Ass.Prof., 大学院・システム情報科学研究院, 助教授 (50237252)
ASADA Hironori Yamaguchi Univ., Faculty of Engineering, Ass.Prof., 工学部, 助教授 (70201887)
|
|---|
| Project Period (FY) |
1998 – 2000
|
| Keywords | Giant magnetoresistance effect / Magnetic thin film / Spin-dependent electron scattering / Spin valve |
|---|
| Research Abstract |
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
|
