  Heat assisted recording is believed as a key technology in order to further
increase the areal density of magnetic recording. In the work of Richter et al.
[Richter et al. J. Appl. Phys. 111, 033909 (2012)] it is stated that storage
densities will be limited to 15 to 20 Tbit/in2 due to thermally induced write
errors. In this letter we propose a composite structure consisting of two
materials with different Curie temperatures. A hard magnetic layer is on top of
a high Tc soft magnetic layer. In this composite material the thermal write
error is negligible up to areal densities of 50 to 100 Tbit/in2. It is shown
that the effective thermal field gradient, which is reduced in this composite
structure, is not relevant for a possible increase of the transition jitter.
The transition jitter is dominated by a small distribution of the Curie
temperature. The smallest jitter is obtained for the composite structure.
