%0 Journal Article
%T Ferromagnetic Resonance Characterization of Nano-FePt by Electron Spin Resonance
%A S. S. Nkosi
%A H. M. Gavi
%A D. E. Motaung
%A J. Keartland
%A E. Sideras-Haddad
%A A. Forbes
%A B. W. Mwakikunga
%J Journal of Spectroscopy
%D 2013
%R 10.1155/2013/272704
%X Electron spin resonance (ESR) measurements at room temperature and X-band microwave frequency were performed on highly crystalline FePt system thin films. Fairly high DC static magnetic field absorption of about 300£¿mT was observed in these films. We attribute the high field absorption to ferromagnetic resonance (FMR). Upon increasing iron content in FePt system, no detectable spin waves modes were identified already at room temperature. This signifies a homogeneous distribution of the magnetization across the films. We qualitatively attributed such homogeneity distribution in the films to self-assembly of these Fe¨CPt system nanoparticles. The results revealed that the FePt system contains hyperfine coupling with sextet exhibiting a phase reversal behaviour compared to FMR line. Both iron content and crystallite size increased the FMR intensity making the films good candidates for large data storage mediums and spintronics. 1. Introduction Magnetic recording media plays a vital role in the development of nonvolatile data storage technologies. Particularly, magnetic hard disk drives are important parts in many devices such as video cameras and computers. The year 1956 marked the generation of first magnetic hard disk with recording density of 2£¿kB/in2 that was successfully built by IBM [1]. Since then, the areal density (the number of bits/unit area on a disk surface) has successively increased [2]. Nowadays, products with an areal density of more than 700£¿GB/in2 are commercially available [3]. The increase in the areal density needs to be continued due to the future demand for information storage that is drastically advancing. Due to advancement in information technology (IT) and computer science, areal density in a level of 1£¿Tb/in2 or more is inevitable. Iron platinum (FePt) nanoparticles (NPs) are actively being pursued as a potential candidate for larger storage capacities on hard-disk drives than any other materials due to its high magnetocrystalline anisotropy (MA) [4]. MA is a process when the atomic structure of a crystal of a certain material introduces preferential direction of magnetisation, and in most cases, it will be the easy axis of magnetisation [5]. This phenomenon is mostly common in ferromagnetic materials. Traditional magnetic recording materials such as Co/Cr have limitations since their magnetic direction of each recording bit would become unstable at room temperature due to thermal fluctuation [6]. FePt does not only possess higher magnetic anisotropy but also possesses better thermal stability [7]; this makes it a better
%U http://www.hindawi.com/journals/jspec/2013/272704/