Properties of high rate sputtered perpendicular recording media

Abstract

Double layered media for perpendicular magnetic recording were made by dc magnetron sputtering. The coercivity of the Co-Cr layer was independent of deposition rate over the range from 0.006 to 1.2 μm/min, when the substrate temperature was kept constant during sputtering. Micro columnar structure of the Co-Cr film was studied by chemical etching. Only the columns were dissolved leaving the column boundaries showing a microhoneycomb structure. From the composition analysis of the etchant, Cr segregated column boundaries were confirmed to exist even in the high rate sputtered films. The Permalloy back layer with coercivity below 1 Oe shows large noise pulses in the reproducing process. Increasing the coercivity to several Oersteds reduced the noise to the amplifier noise level without changing the signal level. Finally, a high recording performance was obtained for the media made by high rate sputtering.