Magnetic properties and viscosity effect of L1₀ FePt film with GePt underlayer

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• 作者：J.L. Tsai ; C.J. Hsu
• 关键词：L1₀ FePt ; Coercivity ; Island-like
• 刊名：Journal of Alloys and Compounds
• 出版年：2008
• 期刊代码：45_09258388
• 类别：ms
• 出版时间：8 May 2008
• 卷：455
• 期：1-2
• 页码：87-91
• 文件大小：512 K

摘要

We explored the GePt underlayer thickness effect on the magnetic properties and microstructure of L1₀ FePt film. The GePt underlayer was deposited on quartz at 800 °C and the thickness changed from 10 to 120 nm. The Ge₂Pt₃ compound was formed and the island-like structure was able to relax the growth stress between Ge₂Pt₃ and quartz when the thickness is smaller than 60 nm. After FePt deposition, the bilayer was post-annealed at 400 °C. In plane coercivity (H_c) decreased from 14 to 2 kOe when the underlayer thickness increased from 10 to 120 nm. First, we suggested L1₀ FePt film is higher ordered (S = 0.71–0.93) on the island-like underlayer and the coercivity are larger than 8 kOe. It is because the island-like Ge₂Pt₃ induced tensile stress on FePt, which enhanced the formation of ordered FePt. The obstacles or pinning sites created by Ge₂Pt₃ island-like surface morphology makes FePt domain wall motion lagging and the coercivity become larger. But the inter-diffusion effect still exists for film with 10 nm Ge₂Pt₃ underlayer at 400 °C. Second, with underlayer thickness 120 nm, the Ge atoms diffused into the FePt film that suppressed the ordering with parameter S = 0.49 and the coercivity was 2 kOe.