以分子束磊晶成長之鐵鉑超晶格多層膜之結構與磁性研究

• Main Author: 周嵩傑
• Other Authors: 戴明鳳
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/28803314777560260451

碩士 === 國立中正大學 === 物理系 === 91 === The FePt film displays a large perpendicular magnetic anisotropy property and is a promising material for high-density perpendicular magnetic recording media. The strength of perpendicular magnetic anisotropy is strongly correlated with its crystal structure. Recent studies showed that doping of inpurity and monolayer superlattice growth can often result in marked change of the transition tempeature of chemical ordering and the magnetic properties. By using the molecular-beam epitaxial technique, 300 Å thick [Fe (x Å)/Pt (x Å)]n (4 ≤ x ≤ 10 or 38 ≤ n ≤ 15) superlattice films were deposited on 100 Å thick Pt buffer layers at 100oC on Al2O3 (0001) or Si(100) substrates. After post annealing at 300oC, 400oC, 500oC and 600oC for an hour, we analyzed the crystal structure and magnetism of FePt superlattice films. The structure was fcc (111) for the [Fe (x Å)/Pt (x Å)]n superlattice films grown on Al2O3 (0001). For the post annealing temperature higher than 400oC, FePt fcc (100) orientation appeared. At the same time, the coercivity of FePt films reached 12 kOe. Furthermore, as decreasing the bilayers thickness, FePt superlattice films formed a hard magnetic phase at a low annealing temperature. On the other hand, the [Fe (x Å)/Pt (x Å)]n superlattice films grown on Si (100) substrates displayed a polycrystal structure. After post annealing at 400oC for an hour, that realized Pt3Si and Fe3Si phases were observed. That indicates that Pt buffer layers can not prevent the diffusion of Si atoms. Therefore, the FePt superlattice films lost its ferromagnetic behaviors after post annealing.