Simulations of time dependence in perpendicular media

We simulated time dependence of magnetisation in single- and double-layer p erpendicular media using a Landau-Lifshitz-Gilbert model with a random fiel d term to represent thermal fluctuations. In the single-layer medium the ti me dependence was large following film saturation but was reduced in the bi layer medium. The time dependence of written bits was also investigated and found to be much lower than in the saturated film case. The time dependenc e was further reduced as the bit density increased. (C) 1999 Elsevier Scien ce B.V. All rights reserved.