Thermal instability at 10 Gbit/in/sup 2/ magnetic recording

The limitation on recording density imposed by thermal stability is systematically studied by a method combining molecular dynamics and Monte Carlo computer simulations. The thermal decay for as long as 6 months has been simulated for written di-bits at the projected anisotropy, grain size, and bit length for 10 Gbit/in/sup 2/ magnetic recording. In the presence of demagnetizing field, a single layer film has little thermal effect at the upper limit of the projected grain sizes, while thermal decay is obvious when grain sizes are at the lower limit. The magnitude of the noise peak does not change significantly while the noisy region becomes wider after thermal decay. Compared with a single layer medium of the same total thickness, a double layer film has much more serious thermal decay and the negative interaction between layers tends to demagnetize the film, therefore making the thermal effect worse. The thermal decay in multilayer media tends to cancel the gain in noise reduction obtained by dividing the film layer at ultrahigh recording density. The effects of magnetostatic and exchange interaction, anisotropy, and grain volume on thermal stability are discussed. >