Fluctuation field and time dependence of magnetization in TbFeCo amorphous rare earth-transition metal thin films for perpendicular magnetic recording

In this work we report on the experimental analysis of the time decay of magnetization in the films of amorphous TbFeCo alloys for perpendicular magnetic recording. It is shown that the experimental results can be explained on the basis of the thermally activated incoherent subnetwork magnetization reversal model. Thermally activated reversal of the transition metal subnetwork and associated reversal of the antiferromagnetically coupled rare-earth subnetwork may result in effective stabilization of the net film magnetization. Experimentally obtained activation diameter value D(a)similar to5-6 nm corresponds to the exchange length or the domain wall width in the films under study. The small activation diameter value combined with high stability factor k similar to 250 mean that the TbFeCo amorphous film should be capable of supporting a thermally stable perpendicular recording at over 100 Gbit/in(2) recording density. (C) 2001 American Institute of Physics.