| Co-Investigator(Kenkyū-buntansha) |
JIMBO Mutsuko DAIDO INSTITUTE OF TECHNOLOGY,INSTITUTEB OF MATERIAL SCIENCE AND TECHNOLOGY,ASSO, 材料科学技術研究所, 助教授 (00115677)
IWATA Satoshi NAGOYA UNIVERSITY,DEPT.ELECTRONICS,ASSOCIATE PROFESSOR, 工学研究科, 助教授 (60151742)
TANJI Takayoshi NAGOYA UNIVERSITY,CENTER FOR INTEGRATED RESEARCH IN SCIENCE AND ENGINEERING,ASSO, 理工科学総合研究センター, 助教授 (90125609)
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| Research Abstract |
Giant magnetoresistance (GMR) effect has been found in a wide variety of materials. Concerning amorphous materials, however, very little has been reported so far. Since amorphous magnetic films have usually excellent soft magnetic properties, such as low coercivity, high permeability and relatively high resistivity, they have been often applied for inductive readout heads. For the GMR, we found that spin valves using amorphous CoFeB exhibit relatively large MR ratios of 4 to 6%. These values are comparable to or even larger than those of crystalline NiFe spin valves. NiO/CoFeB/Cu/CoFeB spin valves with B content of 0 to 10 atm.% were prepared to investigate the dependence of the giant magnetoresistance effect on the thickness of free magnetic layers. In the spin valves, giant magnetoresistance effects were observed even when the free magnetic layers were very thin down to 1 or 0.5 mm. For lower B content, the MR ratio rapidly increased with the increase of the thickness of free magnetic layers, while for higher B content, the MR ratio exhibited the maximum at the thickness which is roughly equal to the mean free path of electrons in the magnetic layers. By using Camley - Barnas model, the value of the MR ratio and the resistivity can be consistently explained if the specular reflection of electrons is considered at the interface between magnetic and nonmagnetic layers.
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