Directly RF-sputtered γ-Fe2O3thin films

RF-sputtered γ-Fe2O3thin films have been proposed for obtaining high bit densities in digital magnetic recording. However, those reported methods of preparation for γ-Fe2O3films involve RF reactive sputtering of Fe or Fe3O4followed by heat treatments for oxidation and reduction. Better control of their properties and savings in processing time and cost are attained by directly sputtered γ-Fe2O3films. We present results of measurements of the structure and magnetic properties of γ-Fe2O3films which were directly sputtered from a Fe3O4target on to glass, Al, and Si substrates. X-ray diffraction patterns obtained for these films showed the characteristic γ-Fe2O3peak distribution. Electron diffraction also exhibited Debye-Scherrer rings of the γ-Fe2O3structure. The in-plane coercivity ranged from 500 to 650 Oe. with squareness of 0.31 to 0.44 and the perpendicular coercivity ranged from 750 to 1000 Oe. with squareness of 0.70 to 0.82. The directly RF-sputtered γ-Fe2O3appears to have perpendicular magnetic anisotropy.