Structural and magnetic properties of HCP-CoCrPt-SiO2 granular media

Granular HCP-(CoCrPt)100-x(SiO2)x thin films with Cr underlayers have been fabricated by sputtering multilayers followed by post-deposition annealing. Magnetic and structural properties of the films for potential applications in magnetic recording media have been investigated in detail. In as-deposited films coercivities exceeding 2.5 kOe have been obtained with SiO2 varying from 8 to 16 vol%; high coercivity of 5.6 kOe and anisotropy of 4.6x106 erg/cm3 have been achieved at low Mrt value (about 0.4 memu/cm2) in the post-annealed films. VSM measurements showed that the magnetic moment lies well in the film plane under proper preparation conditions. Grain isolation in the magnetic layer was improved by segregating SiO2 into grain boundaries and further enhanced by post-deposition annealing. The rapid increase of the coercivity upon annealing is most likely due to the significant decrease in intergranular exchange coupling, as shown by the δM measurement in which the peak value of δM curves changed from a positive value to a negative value upon annealing. Magnetic reversal properties of the films have also been systematically studied. These results show that the HCP-CoCrPt-SiO2 granular film is a promising candidate for ultra-high-density recording media up to 100 Gbit/in2 or beyond because of its low Pt content and desirable properties