Thermal stability of longitudinal media for >20 Gbits/in/sup 2/ recording

The thermal stability of a CoCrPtB-based media for over 20 Gbit/in/sup 2/ recording is investigated by magnetometry and spin stand methods. Recent quaternary and 5-element alloys for longitudinal magnetic recording media show significantly reduced grain sizes compared to Co-Cr-Pt-Ta alloys for the same underlayer structure. Cr segregation was also enhanced and the Cr-rich regions between grains were wider than those of CoCrPtTa media. These resulted in significant gains in S/sub o//N/sub m/ necessary for high density and high data rate recording and also in the degradation of magnetic thermal stability. Although higher densities can be achieved by decreasing the bit aspect ratio, side erasure problems due to flux leakage from narrow write heads are worsened.