| Co-Investigator(Kenkyū-buntansha) |
NAKAI Hisashi Faculty of Electro-Communications, The University of Electro-Communications, Lecturer, 電気通信学部, 講師 (70237204)
SHI J. Faculty of Electro-Communications, The University of Electro-Communications, Research Associate, 電気通信学部, 助手 (70293123)
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| Budget Amount *help |
¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 2001: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2000: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Research Abstract |
In this work, the preparation and characterization of Co-Ti-N films have been conducted. First, we have disclosed the relation between the preparation condition and the structure of the Co-Ti-N films. Co-Ti-N films have been prepared by dc sputtering of Co-Ti complex target in Ar +N_2 gas mixture. For the films deposited at appropriate N_2 partial pressure, the reaction between Ti and N occurs to form TiN during post-deposition thermal anneal. As a result Co and Ti separate with each other, to form Co-TiN nano-composite. The sizes of Co and TiN grains in the longitude direction are about 10 nm in diameter. And fiber-like structure is developed along the normal direction of the film surface. Next the magnetic properties of the Co-TiN nanocomposite films have been investigated. It has been found Co-TiN nanocomposite films with their thickness less than 100 nm show similar magnetization behavior in both longitude and perpendicular directions. However, those films with their thickness abov
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e 100 nm show perpendicular magnetic anisotropy, I.e. perpendicular direction becomes the easy axis of magnetization. Furthermore, the dependence of magnetic properties on the thermal anneal condition and film structure have been investigated. The as-deposited films almost do not show ferromagnetic performance. When the films were annealed at 400 - 700℃, they show clearly ferromagnetic performance and the saturation magnetization increased with increasing anneal temperature. This is because that in the as-deposited state, Co atoms are bonded to Ti and N, upon thermal anneal at elevated temperature, N atoms preferentially react with Ti atoms, therefore, Co is separated. The magnetic properties of the Co-TiN films also depend strongly on the amount of N incorporated into the films. When N amount is too small, the phase separation can not fully proceed. On the other hand, when the N amount is too large, Co is also nitrided except Ti. Both cases will impair the saturation magnetization. Therefore it is important to control the N amount in the film.
Beside the magnetic properties, we have found that the resistivity and hardness of Co-TiN nanocomposite films are very high compared with metal and alloy films.
According to the result of this research work, we consider the Co-TiN-based nanocomposite films very promising as ultra-high density perpendicular magnetic recording media. Less
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