2005 Fiscal Year Final Research Report Summary
FePt hybrid high density recording media and optically assisted recording
| Project/Area Number |
16560602
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Composite materials/Physical properties
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| Research Institution | Nihon University |
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Principal Investigator |
NAKAGAWA Katsuji Nihon University, College of Science and Technology, Professor, 理工学部, 教授 (20221442)
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| Co-Investigator(Kenkyū-buntansha) |
ITOH Akiyoshi Nihon University, College of Science and Technology, Professor, 理工学部, 教授 (60059962)
TSUKAMOTO Arata Nihon University, College of Science and Technology, Assistant Professor, 理工学部, 講師 (30318365)
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| Project Period (FY) |
2004 – 2005
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| Keywords | Super paramagnetic problem / Optically assisted recording / Opt-magnetic hybrid recording / Composite films / Rapid thermal annealing method / Ll_0 FePt particulate / TbFeCo / Domain wall coercivity |
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| Research Abstract |
FePt is thought to be one of promising materials for high density recording in combination with a heat assisted recording because of its high magnetic anisotropy and the capability of forming small grains. We fabricated the FePt film on thermal oxidized Si substrate by rapid thermal annealing (RTA), and investigated the order parameter and the orientation parameter as a function of annealing temperature. We also observed grains by a transmission electron microscope (TEM).
As deposited films of FePt by a sputtering method are continuous films, however after RTA, they become small grains of (001) oriented Ll_0 phase structure. The average grain diameter strongly depends on the film thickness of as sputtered film. The smallest average diameter was 7 nm. We investigated the effect of Cu substitution within FePt grains prepared by RTA. (001) orientation is strongly enhanced by Cu substitution. Furthermore, the TbFeCo/FePt composite film shows higher domain wall coercivity by exchange coupling effect between TbFeCo and FePt.
Thermal flow control in media during recording process is one of the important issues for optically assisted recording. To explore possibilities of reduction of cooling time, the time-evolution of the 3-dimensional thermal distributions in the multilayered recording films is calculated by solving the thermal equation numerically. Typical film structure is as follows : SiN(20 nm)/TbFeCo(20 nm)/SiN(10 nm)/Au(50 nm)/SiN(10 nm)/glass substrate. Appropriate thermal flow control in the recording layer quenches the motion of domain wall by optimizing the light intensity distribution and thermal diffusion in every layer in multi layered media.
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