1999 Fiscal Year Final Research Report Summary
Magnetic properties of micro-structured exchange coupled bilayers
| Project/Area Number |
09450229
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical properties of metals
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
OTANI Yoshichika Graduate School of Engineering, Tohoku University, Associate Professor, 大学院・工学研究科, 助教授 (60245610)
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| Co-Investigator(Kenkyū-buntansha) |
KITAKAMI Osamu Research Institute of Scientific Measurement, Tohoku University, Associate Professor, 科学計測研究所, 助教授 (70250834)
SHIMADA Yutaka Research Institute of Scientific Measurement, Tohoku University, Professor, 科学計測研究所, 教授 (00006157)
FUKAMICHI Kazuaki Graduate School of Engineering, Tohoku University, Professor, 大学院・工学研究科, 教授 (00005969)
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| Project Period (FY) |
1997 – 1999
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| Keywords | Exchange coupling / Domain structure / Ferromagnetic dots array / Ferromagnetic wires / Antiferromagnetic domain wall / Magnetoresistance / Antiferromagnet |
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| Research Abstract |
The purpose of this study is to fabricate 3 dimensionally micro-structured exchange coupled bilayers, and to clarify a responsible mechanism for the exchange coupling field in relation to formation of the antiferromagnetic domains and walls. Amongst transition metal alloys and oxides, Cr-Al or NiO was chosen as an antiferromagnet and FeィイD220ィエD2NiィイD280ィエD2 permalloy was chosen as a ferromagnet. After the structural analyses on the grain size and crystallographic orientations between the ferromagnetic and antiferromagnetic layers with using X-ray diffractometer, atomic force microscope and electron microscope, submicron sized exchange coupled bilayers were fabricated by means of electron-bean lithography. The magnetic domain structure as well as magneto-transport properties were then carefully examined with magnetic force microscope and 4 terminal methods. For the first time, the magnetization reversal processes occurring in the sub-micron region was obtained by analyzing the anisotropy magnetoresistance and the planar Hall effects. The results were compared with the demagnetization curves calculated by micromagnetic simulation. It was found that the exchange coupling field varies proportional to the inverse of the coupling area. Furthermore the slope of the variation was found to reflect the degree of roughness at the interface which determines the strength of the net exchange coupling due to the random exchange field.
From this experimental study, the exchange coupling field was shown to be controlled by adjusting the coupling area in submicron scale, which determines the antiferromagnetic domain size.
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