Low noise FeAlSi soft magnetic under-layer for CoPtCrO double-layered perpendicular recording media

Abstract

FeAlSi multi-layered structure successfully reduced the noise compared with a mono-layered film. Optical surface analyzer also revealed that the films did not show any clear magnetic domains of spike noise source in the whole disk. TEM image of low noise film showed wide grain boundaries between 200 to 500 nm diameter FeAlSi grain clusters. The coercivities of films were significantly reduced when they were laminated. Along with the cluster isolation effect, the interlayer magnetic coupling of the multi-layered FeAlSi films also effectively reduce the noise. Double-layered perpendicular medium with a CoPtCrO recording layer and a multi-layered FeAlSi soft under-layer showed 25.8 dB SNR at 400 kBPI and 0.36 /spl mu/m read truck width, and 2.5/spl times/10/sup -7/ BER on a spin stand was achieved.