We have started the research on espin-filterfdevices applicable for future storage or switching devices. Using these devices, we will be able to utilize not only electron charges but electron spin states. The adoption of half-metallic materials, such as Fe3O4, as the ferromagnetic layers in magnetic tunneling junctions is an attractive approach for realizing espin-filterf devices with large spin polarization.
[Fe3O4/ Ru] films were deposited using a dual ion beam sputtering method at room temperature. Highly crystalline [Fe3O4/ Ru] films could be obtained by tuning the Kr ion beam energy to exactly 160 eV during the film deposition. We have succeeded in fabricating 100-nm-dimension [Co-Fe/Al-O/Fe3O4] pillar structures using electron beam lithography and ion beam milling processes. Barrier heights for these pillars of approximately 2.6 eV are attained when the pillar size is larger than 120 nm.
|||B. Dieny, V. S. Speriosu, S. S. P. Parkin, B. A. Gurney, D. R. Wilhoit, and D. Mauri, gGiant magnetoresistive in soft ferromagnetic multilayers,h Physical Review B, 43, (1), pp. 1297?1300 (1991).|
|||J.M. Daughton, gMagnetic tunneling applied to memory,h Journal of Applied Physics , 81 , (8), pp. 3758-3763 (1997).|
|||K. Aoshima and S.X. Wang, gFe3O4and its magnetic tunneling junctions grown by ion beam deposition,h Journal of Applied Physics, 93, (10), pp. 7954-7956 (2003).|
|||Z. Zhang and S. Satpathy,gElectron states, magnetism, and the Verwey transition in magnetite,h Physical Review B, 44, (24), pp. 13319-13331 (1991).|
|||Y. Miyamoto, K. Machida, N. Hayashi, T. Tamaki and H. Okuda, gDeposition of [Ni-Fe/Al-O/Co-Fe] Films with Tunneling Magnetoresistance Effect using The Interfacial Modulation Technique,h Journal of Applied Physics,89, (11), pp. 6647-6649 (2001).|
|||Y. Miyamoto, K. Machida, N. Hayashi, T. Tamaki, H. Okuda and M. Naoe, gDeposition of Stoichiometric Ta2O5Films for TMR Devices by Reactive Ion Beam Sputtering,h Ferrites: Proceedings of ICF8., pp. 728-730 (2001).|
|||K. Nishikawa, M. Tsunoda, S. Ogata and M. Takahashi, gNew Plasma Source with Low Electron Temperature for Fabrication of an Insulating Barrier in Ferromagnetic Tunnel Junctions,h IEEE Transactions on Magnetics,35, (5), pp. 2718-2720 (2002).|
|||Y. Miyamoto, K. Kuga, N. Hayashi, K. Machida and K. Aoshima, gInfluence of Magnetic Field on the Tunneling Current in Magnetic 10-nm-scale Point Contact Junctions using Tunneling Atomic Force Microscopy,h Journal of Applied Physics, 95, (11), pp. 7246-7248 (2004).|
|||J.G. Simmons, gGeneralized Formula for the Electric Tunnel Effect between Similar Electrodes Separated by a Thin Insulating Film,h Journal of Applied Physics, 34, (6), pp. 1793-1803 (1963).|
|Dr. Yasuyoshi MIYAMOTO
He received the B.S., M.S. and Ph.D. degrees in physical electronics from Tokyo Institute of Technology in 1993, 1995 and 1998, respectively. He was a research fellow of the Japan Society for the Promotion of Science (JSPS) from 1996 to 1998. He joined NHK in 1998 and has been with NHK Science and Technical Research Laboratories. He was also a visiting scholar at Stanford University, California, from 2001 to 2002. He has been engaged in the magnetic materials and magnetic thin-film devices for recording and the fundamental research on spin-electronics. He is a member of the Institute of the Electrical and Electronics Engineers (IEEE) and the Magnetics Society of Japan (MSJ).
Mr. Hirotaka SHIINOHe received the B.S. and M.S. degrees in engineering science and fundamental energy science from the Kyoto University in 1998 and 2000, respectively. He joined NHK in 2000. Since 2003, he has been with NHK Science and Technical Research Laboratories. He has been engaged in the researching on spin-tunneling devices and related materials.
|Mr. Kiyoshi KUGA
He received the B.S. and M.S. degrees in electrical engineering from Waseda University, Tokyo, in 1981 and 1983, respectively. He joined NHK in 1983. Since 1986, he has been with NHK Science and Technical Research Laboratories. He has been engaged in the researching on the perpendicular magnetic recording media, and fundamental research on spin-electronics including ferromagnetic semiconductors and spin-filter devices. He is currently a senior research engineer of materials science division. He is a member of the Magnetics Society of Japan (MSJ), the Japan Society of Applied Physics (JSAP) and the Institute of Image Information and Television Engineers of Japan (ITE).