MAGNETIC AND RECORDING CHARACTERISTICS OF COCRTA/CR THIN-FILM MEDIA PREPARED BY FT SPUTTERING

Magnetic properties and media noise in CoCrTa/Cr longitudinal magnetic recording media prepared by Facing Targets (FT) sputtering has been studied. All CoCrTa magnetic films in this study were deposited at Ar gas pressure of 2 mTorr and 500 Å in thickness. Coercivity of a film deposited on a substrate at room temperature depended strongly on Cr layer thickness and Ar gas pressure. The film with Cr underlayer deposited at Ar gas pressure PAr as low as 0.2 mTorr in thickness range from 100 to 1, 000 Å exhibited higher coercivity than one at PAras high as 10 mTorr. Coercivity of the film abruptly increased from 400 to 1, 100 Oe by annealing at 400 °C even for time as short as 15 minutes. Media noise normalized by amplitude of isolated pulse signal of magnetic disk with CoCrTa/Cr films has been evaluated. Normalized media noise also depended on Ar gas pressure and thickness of Cr underlayer. Reduction in media noise of the films prepared at high Ar gas pressure with increase of Cr underlayer thickness seems to be attributed to the decrease in coupling force among ferromagnetic grains due to clear column formation in microstructure of Cr underlayer. © 1990 IEEE