Magnetic Properties of FePt Nanoparticles Prepared by a Micellar Method

• Main Authors: Gao Y, Zhang XW, Yin ZG, Qu S, You JB, Chen NF
• Format: Article
• Language: English
• Published: SpringerOpen 2009-01-01
• Series: Nanoscale Research Letters
• Subjects: FePt nanoparticles; Reverse micelles; Self-assembly; Interparticle exchange coupling; Magnetic recording
• Online Access: http://dx.doi.org/10.1007/s11671-009-9433-4

<p>Abstract</p> <p>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 <it>L</it>1₀ FePt was achieved for samples annealed at temperatures above 700 &#176;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&#8211;Henkel plots (&#916;<it>M</it> measurement). The &#916;<it>M</it> 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.</p>