1999 Fiscal Year Final Research Report Summary
MICROSTRUCTURAL CONTROL OF THE INTERFACE FOR SPIN-VALVE GMR THIN-FILMS BY APPLYING THE ULTRA CLEAN SPUTTERING PROCESS
| Project/Area Number |
09355010
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
電子デバイス・機器工学
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
TAKAHASHI Migaku GRADUATE SCHOOL OF ENGINEERING, TOHOKU UNIV., PROFESSOR, 大学院・工学研究科, 教授 (70108471)
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| Co-Investigator(Kenkyū-buntansha) |
KIRA Tooru PRECISION TECHNOLOGY DEVELOPMENT CENTER, SHARP CO., SENIOR RESEARCHER, 生産技術開発本部・精密技術開発センター, 技師長(研究職)
TSUNODA Masakiyo GRADUATE SCHOOL OF ENGINEERING, TOHOKU UNIV., RESEARCH ASSOCIATE, 大学院・工学研究科, 助手 (80250702)
SHOJI Hiroki GRADUATE SCHOOL OF ENGINEERING, TOHOKU UNIV., ASSOCIATE PROFESSOR, 大学院・工学研究科, 助教授 (70241528)
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| Project Period (FY) |
1997 – 1999
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| Keywords | THIN FILMS / MAGNETIC THINI FILMS / ULTRA HIGH VACUUM / SPUTTERING |
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| Research Abstract |
The extremely clean sputtering process (XC process) was newly introduced in the fabrication of ultra-thin spin valves to control the microstructure and to establish the excellent magnetic properties. The relation between cleanness during film deposition process and the magnetic properties of spin valve elements has been discussed in connection with their microstructure. Sub./Ta/Ni-Fe/Mn-Ni/Ni-Fe and Sub./Ta/Ni-Fe/Mn-Ir/Ta quadrilayers were fabricated under the different purity of the sputtering atmospheres. Strength of the exchange anisotropy measured at room temperature was enhanced in very thin F/AF bilayer fabricated under the XC-process, comparing with the bilayer fabricated under a lower graded (LG-) process, which only differed in the base pressure of the sputtering chamber : 10ィイD1-7ィエD1 Torr order. From a structural analysis and a temperature dependence of the exchange anisotropy of the bilayers, grains in the bilayers fabricated under the XC-process were found to be enlarged a
… More
nd that the enhancement of exchange anisotropy was caused by the enlargement of antiferromagnetic grains, which suppress thermal agitation and lowering the local blocking temperature. For the electron transport, the enlargement of the grains observed in the XC-processed films also played an important role. The decrease of grain boundaries and impurities in the films, reduced saturated resistivity of the spin valves, Sub. Ta/Ni-Fe/Co/Cu/Co/Mn-Ir/Ta, with lowering the impurity level in the sputtering atmosphere and resulted in the increase of the MR ratios. The MR ratio of tan optimized spin valve fabricated under the XC-process achieved to 9.7%, even in the total thickness of 148 【encircledA】 except for the capping Ta layer, while that of the LG-processed spin valve dropped to 0.9% due to the vanish of the exchange anisotropy. We concluded that the extremely clean sputtering process is greatly effective to realize ultra-thin spin valves and that to avoid rumpling interfaces of them it important to induce the adequate magnetic properties. Less
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