The effect of sputtering pressure on microstructure and recording performance of high-density magnetic recording media

Abstract

Understanding the magnetic properties of thin films applicable to high density recording requires detailed knowledge of the microstructure and microchemistry of the film. Interactions such as exchange and magnetostatic as well as anisotropies have been shown theoretically to influence the magnetic properties and recording characteristics of the media. These magnetic interactions and anisotropies are very sensitive to microstructure. This study reports the efTcct of sputtering pressure on the microstructurc and magnetic properties of thin CoPtCr films. The relation between the microstructural features and the magnetic interactions will be discussed.The film structure, C/Co77Pt6Cr17/Cr, was sequentially sputtered onto Si and NiP/AlMg substrates precleaned by an rf plasma. The thicknesses were 25/25-60/100 nm respectively. Sputtering pressures ranging from 3 to 24 mtorr were investigated. The magnetic properties of the films (coercive field, Hc, coercive squareness, S*, remanent and saturation moments, Mrand Ms) were determined by vibrating sample magnetometry. The magnetic recording measurements were made with thin film inductive write heads and experimental shielded magnetoresistive read head with a track width of about 10μm. The head-media spacing was 5 μin. Noise voltages for transition densities up to 3000 fc/mm were determined in the usual fashion. The microstructures were studied using the JEOL JEM 2000 FX and 4000 EX transmission electron microscopes.