(A) study on thermally stable ultra-high density granular type = 열적으로 안정한 과립형 초고밀도 수직자기기록매체에 관한 연구

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The perpendicular recording films of CoCrPt ternary grains isolated by various oxides are the most widely used recording layer. Small grain size is a very critical requirement for high density recording. Grain core size of $CoCrPt-SiO_2$ media could be reduced by grain refinement in the Ru(Cr) underlayer with oxygen reactive sputtering. As grain size decreases, thermal stability of the present $CoCrPt-SiO_2$ media becomes a more critical issue because the energy barrier to the spontaneous magnetization reversal depends on particle volume and anisotropy constant. It can be relieved by using higher $K_u$ materials than conventional $CoCrPt-SiO_2$. However, considering the write field of the present writing heads, there are not many choices in media material selection. In this study, stacked structure of different magnetic materials in $K_u$ was proposed in order to overcome this dilemma. In the first part, exchange decoupling of $CoCrPt-SiO_2$ film is discussed. $Al_2O_3$ and MgO were examined as grain boundary segregation materials besides $SiO_2$. $SiO_2$ incorporated CoCrPt layers had higher coercivity and squareness than those of MgO and $Al_2O_3$ cases. This would be attributed to the well-isolated CoCrPt grains by $SiO_2$. The different behaviors are thought to be associated with different kinetics of diffusion for the different oxide elements rather than thermodynamic energy. The effect of Ru layer morphology on the physical grain separation in recording layer is investigated in order to lessen the intergranular exchange coupling. A two-step Ru underlayer was employed for both good texture development and better grain isolation. Narrow c-axis dispersion is attributed to the bottom Ru layer deposited at low pressure, and physically isolated top Ru grains are induced by high pressure deposition. When CoCrPt layers are deposited on the top of the well isolated Ru grains, there is one to one grain relationship between Ru and CoCrPt grains, therefore CoC...
Advisors
Lee, Taek-Dongresearcher이택동researcher
Description
한국과학기술원 : 신소재공학과,
Publisher
한국과학기술원
Issue Date
2008
Identifier
303606/325007  / 020037243
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 신소재공학과, 2008. 8., [ ix, 128 p. ]

Keywords

perpendicular magnetic recording; CoCrPt; hard disk drive; 수직자기기록; CoCrPt; 하드디스크드라이브

URI
http://hdl.handle.net/10203/49852
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=303606&flag=dissertation
Appears in Collection
MS-Theses_Ph.D.(박사논문)
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