RECORDING PROPERTIES OF A DOUBLE-LAYER MEDIUM OF PERPENDICULAR Fe-Co-O / IN-PLANE Co-O UNDERLAYER

A double-layer medium composed of partially oxidised perpendicular Fe-Co alloy film (Fe-Co-O) / partially oxidised in-plane Co film (Co-O) was designed and tested for a still video floppy disk system using a conventional drive. The in-plane Co-O underlayer was deposited by rf magnetron sputtering at low Ar gas pressure, and showed isotropy in the film plane. Magneto-striction was presumed to play an important role in the in-plane anisotropy. In this medium composition, the in-plane Co-O underlayer is relatively thick (ca. 2000Å) compared to hitherto investigated underlayers, which results in a high output. The partially oxidized perpendicular top layer gives rise to a high recording density and a good tribology. This medium proved to have a good practical performance.