Synthesis of Magnetic Nanoparticles by Sputtering
- PDF / 1,490,110 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 66 Downloads / 207 Views
0980-II05-45
Synthesis of Magnetic Nanoparticles by Sputtering Mai Miyata, Kyosuke Kishida, Katsushi Tanaka, and Haruyuki Inui Department of Materials Science and Engineering, Kyoto University, Sakyo-ku, Kyoto, 606-8501, Japan ABSTRUCT The influence of experimental condition on morphology of FePt and Sm-Co nanoparticles synthesized by sputtering in a relatively high gas pressure has been studied. The sputtering apparatus is equipped with an annealing furnace that enables pre-deposition annealing of the nanoparticles. The effect of the annealing temperature on the ordering to the L10 FePt nanoparticles was also investigated. The morphology of the particles depends on a gas pressure and gas flow rate, but the sensitivity to experimental condition differs between FePt and Sm-Co. The morphology and domain structure of FePt nanoparticle are relatively the same in a wide range of experimental condition, whereas those of Sm-Co nanoparticle are significantly changed by variation of a gas pressure. FePt nanoparticles annealed in the annealing furnace prior to their deposition onto the substrate have the ordered L10 phase, which has an advantage for producing a magnetic recording media. INTRODUCTION Magnetic nanoparticles are attracting considerable attention due to their potential application as a data storage medium with the ultimate goal of storing one data bit per a particle. Since magnetic stability of an individual particle scales with KuV (where Ku is the anisotropy constant and V is the particle volume), magnetic materials with a high magnetic anisotropy constant is required to decrease the individual particle volume [1]. FePt and SmCo5, which have higher magnetic anisotropy constants compared with the currently used Co-Cr-based alloys, are promising candidates for future high density magnetic recording media applications [2]. The thermodynamic equilibrium structure of FePt is the chemically ordered L10 phase with high anisotropy. However, particles made by both chemical and physical methods are disordered fcc phase. FePt nanoparticles must be annealed at a high temperature after deposited onto a substrate to induce the phase transformation from the disordered fcc to the ordered L10 phase. Such post-deposition annealing induces agglomeration of the previously separated particles and thermal degradation of the substrates [3-6]. In order to avoid these difficulties, we employ a sputtering apparatus with relatively high gas pressures equipped with an annealing furnace [7]. We synthesis ordered L10-FePt and SmCo5
Figure 1. Schematic drawing of the experimental apparatus. nanoparticles by this apparatus, and observe the morphology changes of the particles in different experimental conditions. EXPERIMENTAL DETAILS Figure 1 shows a schematic drawing of the experimental apparatus, which is composed of a nucleation chamber, an annealing furnace and a deposition chamber. The particles precipitate in the nucleation chamber from gas that is magnetron sputtered in a relatively high Ar gas pressure. The particles are carried to
Data Loading...
