Crystallographic and Magnetic Properties of CoCrPt Thin Films Investigated Using Single-Crystal Perpendicular Magnetic T
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Crystallographic and Magnetic Properties of CoCrPt Thin Films Investigated Using Single-Crystal Perpendicular Magnetic Thin Film Samples Masaaki Futamoto, Kouta Terayama1, Katsuaki Sato1, Nobuyuki Inaba2, and Yoshiyuki Hirayama Central Research Laboratory, Hitachi Ltd. Kokubunji, Tokyo 185-8601, Japan 1
Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
2
Development and Technology Division, Hitachi Maxell Ltd., Tsukuba, Ibaraki, 300-2496
ABSTRACT Conditions to prepare good single-crystal CoCrPt magnetic thin film with the easy magnetization axis perpendicular to the film plane were investigated using oxide single-crystal substrates, Al2O3(0001), LaAlO3(0001), mica(0001), SrTiO3(111), and MgO(111). The best CoCrPt(0001) single-crystal thin film was obtained on an Al2O3(0001) substrate employing a non-magnetic CoCrRu underlayer.
The
crystallographic quality of single-crystal thin film was investigated using X-ray diffraction and high-resolution transmission electron microscopy.
Some intrinsic magnetic properties (Hk, Ku) were
determined for the single-crystal CoCrxPty thin films for a compositional range of x=17 – 20at% and y=0 – 17at%. INTRODUCTION Co-based alloy thin films are used as magnetic recording media in hard disk drives. The areal density will continuously increase to 100 – 200 Gb/in2 in the near future. Perpendicular magnetic recording is expected to replace longitudinal magnetic recording to keep the thermal stability of recorded information at high densities. Improvements of magnetic properties while enhancing thermal stability are important issues for designing perpendicular magnetic recording media.
The thermal stability and recording
characteristics of future recording media have been studied mainly by computer simulation employing basic magnetic properties of Co-alloy materials such as magneto-crystalline anisotropy energy (Ku), exchange stiffness constant, Curie temperature, etc.
However it has not been easy to determine these
intrinsic basic magnetic properties using a polycrystalline magnetic thin film which consists of very small crystalline grains with complicated microstructure. In order to investigate the basic magnetic properties accurately, it is desirable to use well-defined single-crystal thin films. Single crystalline Co-based alloy thin films with the easy magnetization axis perpendicular to the film plane have been prepared using Ti and Ru underlayers on mica(0001) substrates [1,2], and using a Ti/Ag composite underlayer on Si(111) substrates [3].
However, the Co-based alloy single-crystalline thin
films are reported to include some crystallographic defects such as sub-grain boundaries and a small fraction of fcc Co-alloy.
We have recently found that Co-alloy single-crystal thin films with the c-axis
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