Magnetic properties and microstructure of FePt-Ag2Se particulate films and exchange-coupled Fe/FePt-Ag2Se films

• Main Authors: Hsueh-Wei Tai, 戴學暐
• Other Authors: 蔡佳霖
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/33361725499780714072

碩士 === 中興大學 === 材料科學與工程學系所 === 99 === Multilayers Ag/[Ag2Se(t)/FePt(1nm)]10 (thickness t = 0.1-0.4 nm) were alternately deposited on a glass substrate and subsequently annealed by rapid thermal process (RTP). After RTP, the interface between FePt and Ag2Se was inter-mixed to form particulate films. The Ag/(Ag2Se/FePt)10 particulate film showed perpendicular magnetization. Compared to Ag/FePt bilayer, the grains size of the L10 FePt decreased from 9.8 nm to 7.7 nm and uniformly separated when the total thickness of Ag2Se intermediate layer increases to 1 nm. Then chose multilayers Ag/[Ag2Se(0.1 nm)/FePt(1nm)]10 as hard layer, the Fe layers with thickness of 1nm, 3nm, 5nm were deposited on FePt-Ag2Se particulate films at room temperature. The Fe/(FePt-Ag2Se) particulate film shows perpendicular magnetization. The magnetization was increased and coercivity was decreased with Fe layer thickness. When the Fe layer thickness increased up to 5nm, two-steps in-plane magnetization curve was found. A soft/hard (FePt/Fe)/(FePt-Ag) and (Fe/FePt)/(FePt-Ag) trilayer with perpendicular magnetization was prepared on a glass substrate. Inserting disordered FePt layer allowed modification of the Fe/(FePt-Ag) sharp interface to (Fe/FePt)/(FePt-Ag) graded interface. The out-of-plane coercivity field was reduced as a function of the FePt thickness because the interface coupling between Fe and FePt-Ag was weakened. The coercivity was inversely proportional to the FePt thickness and evidenced to be the pinning effect at the graded interface. When the interlayer was changed to Fe layer, the coupling between disordered FePt and ordered FePt-Ag film was tuned by the thickness of Fe layer and shown the difference in in-plane hysteresis loops. When the Fe layer is 1 nm, the FePt/Fe/FePtAg film shows perpendicular magnetization with linear in-plane magnetization. The optimal perpendicular magnetization of FePt/Fe(1nm)/FePt-Ag film was contributed mainly from ordered FePt-Ag layer and the magnetization of disordered FePt layer was mediated by thin Fe layer. The Ag(1 nm)/FePt(10 nm) bilayer films were deposited on the ultrathin quartz substrate (110μm) and subsequently annealed by rapid thermal process (RTP).Then measured curvature and stress of the sample by PSC stress analyzer. When annealing temperature increased to 500 oC, the grains affected by grain-growth stress and thermal stress, it presented tensile stress. After 500 oC, the grains began to form island-like grain because of excessive stress would be released. When annealing time increased up to 5 minutes, the grain growth from island-like films to continues films when it affected grain-growth stress.