Nanostructure of CoPtCr&ndash;SiO<SUB>2</SUB> Granular Films for Magnetic Recording Media

Abstract

Structural properties of CoPtCr-SiO 2 magnetic recording films grown on Ru or Pt seed layers prepared by UHV-magnetron sputtering were studied by high resolution transmission electron microscopy (HRTEM), electron energy loss spectroscopy (EELS) and energy filtered transmission electron microscopy (EFTEM). CoPtCr grown on Ru seed layers together with SiO 2 forms a well-isolated structure composed of CoPtCr fine grains of 10 nm diameter surrounded by amorphous SiO 2 , whereas CoPtCr grown on Pt seed layers together with SiO 2 forms a network structure composed of CoPtCr crystal of 5 nm size. These structural features made differences in their magnetic properties. The HRTEM and EFTEM studies revealed that cylindrical crystalline grains composed of CoPtCr and Ru are formed for CoPtCr-SiO 2 /Ru samples, whereas SiO 2 are aggregated around the boundary between relatively large Pt grains and magnetic layers without obstructing the epitaxial growth of CoPtCr on Pt, not resulting in the cylindrical CoPtCr grains. Lattice spacings of CoPtCr grown on Pt with SiO 2 are 0.7% expanded in comparison with CoPtCr grown on Pt without SiO 2 . The EELS studies suggested that Co and Cr atoms are partly oxidized by SiO 2 addition for both samples and Cr atoms are more oxidized for CoPtCr-SiO 2 /Pt samples.

Preparation of Co–Ag films by direct and pulse electrochemical methods

“…Chemicals used were AgClO 4 Electrochemical experiments were carried out in a conventional three-electrode cell using an Autolab with PGSTAT30 equipment and GPES software. Working electrodes were vitreous carbon (Metrohm) and silicon with Ti/ Ni seed layer (Si/Ti(100 nm)/Ni(50 nm)) supplied by IMB-CNM.…”

“…The study of granular materials containing fine magnetic particles embedded in a non-magnetic metallic matrix has produced widespread experimental and theoretical work, due to the potential application of these materials in magnetic sensors and read-head devices [1][2][3][4][5][6]. In this line, the Co-Ag system present interest because, at equilibrium, cobalt is immiscible with silver, thus giving easily sharp interfaces between the magnetic clusters and the non-magnetic matrices [7].…”