title: Magnetic Properties of FePt Nanoparticles Prepared by a Micellar Method.
abstract: FePt nanoparticles with average size of 9 nm were synthesized using a diblock polymer micellar method combined with plasma treatment. To prevent from oxidation under ambient conditions, immediately after plasma treatment, the FePt nanoparticle arrays were in situ transferred into the film-growth chamber where they were covered by an SiO2 overlayer. A nearly complete transformation of L10 FePt was achieved for samples annealed at temperatures above 700 °C. The well control on the FePt stoichiometry and avoidance from surface oxidation largely enhanced the coercivity, and a value as high as 10 kOe was obtained in this study. An evaluation of magnetic interactions was made using the so-called isothermal remanence (IRM) and dc-demagnetization (DCD) remanence curves and Kelly-Henkel plots (ΔM measurement). The ΔM measurement reveals that the resultant FePt nanoparticles exhibit a rather weak interparticle dipolar coupling, and the absence of interparticle exchange interaction suggests no significant particle agglomeration occurred during the post-annealing. Additionally, a slight parallel magnetic anisotropy was also observed. The results indicate the micellar method has a high potential in preparing FePt nanoparticle arrays used for ultrahigh density recording media.
authors.affiliation: Key Lab of Semiconductor Materials Science, Institute of Semiconductors, CAS, Beijing, 100083, People's Republic of China. xwzhang@semi.ac.cn.
authors.forename: Y
authors.initials: Y
authors.lastname: Gao
authors.forename: Xw
authors.initials: X
authors.lastname: Zhang
authors.forename: Zg
authors.initials: Z
authors.lastname: Yin
authors.forename: S
authors.initials: S
authors.lastname: Qu
authors.forename: Jb
authors.initials: J
authors.lastname: You
authors.forename: Nf
authors.initials: N
authors.lastname: Chen