Synthetic ferrimagnetic media for over 100 Gb/in2 longitudinal magnetic recording

Synthetic ferrimagnetic media (SFM) technology to achieve longitudinal magnetic recording over 100 Gb/in(2) is reported. SFM is made using an initial or stabilization layer and a top magnetic layer separated by a thin Ru spacer layer. The magnetic anisotropy (K-U) of the stabilization layer is found to be one of the key parameters for extending this technology to higher densities. A stabilization layer with K-U < 0. 5 x 10(6) erg/cm(3) can be used for reducing the M(r)delta (remanent magnetization and thickness product), but with a minimal contribution to the thermal stabilization of SFM A higher K-U of the stabilization layer contributes substantially to the thermal stability of SFM, with the energy barrier being increased by approximately 55% of the anisotropy energy of the stabilization layer. This enables utilization of thinner top magnetic layers or smaller grain sizes, which leads to better signal-to-noise ratios. A recording density of 106 Gb/in(2) is demonstrated using an SFM with a coercivity of 3900 Oe, M(r)delta of 0.37 memu/cm(2), and a thermal stability performance better than -0.01 dB/decade was observed at 400 kfci. Furthermore, an SFM with good thermal stability could be made at very low M(r)delta of 0. 15 memu/cm(2) and schemes for further advances are suggested. (C) 2002 Elsevier Science B.V. All rights reserved.