Coercivity variation in exchange-coupled Fe/FePt bilayer with perpendicular magnetization

• Published in: Thin solid films 2010-10, Vol.518 (24), p.7271-7274
• Main Authors: Tsai, Jai-Lin, Tzeng, Hsin-Te, Liu, Bing-Fong
• Format: Article
• Language: English
• Subjects: Coercivity; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Exchange; Ferrous alloys; Hysteresis loops; Intermetallics; Iron; Iron compounds; Magnetization; Perpendicular magnetization; Physics; Platinum compounds; Remanence ratio; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2010.04.087

The soft/hard Fe/FePt film with perpendicular magnetization has been deposited on a glass substrate. The (001) oriented L1 0 FePt film was obtained when annealed by rapid thermal process at 800 °C and a Fe layer was deposited at room temperature with thicknesses of 2 nm to 20 nm. Controlling the Fe layer thickness allowed modification of the hysteresis loops from out-of-plane rigid magnet to in-plane exchange-spring like magnet due to the nanometer scale interface coupling. When the Fe layer thickness increased to 2 nm, the out-of-plane coercivity is reduced to 5.9 kOe but the remanence ratio (0.98) is still high. The Fe (2 nm)/FePt film shows perpendicular magnetization with linear in-plane hysteresis loop. The remanence ratio is reduced to 0.85 when the Fe layer thickness increased to 5 nm. When the Fe layer thickness was varied up to 10–20 nm, the in-plane hysteresis loop shows exchange-spring like behavior with two-step magnetization reversal processes. The films with perpendicular coercivity were moderated by the thickness of soft magnetic layer.