THERMAL-INSTABILITY AT 10-GBIT IN(2) MAGNETIC RECORDING/

The limitation on recording density imposed by thermal stability is sy stematically studied by a method combining molecular dynamics and Mont e Carlo computer simulations. The thermal decay for as long as 6 month s has been simulated for written di-bits at the projected anisotropy, grain size, and bit length for 10 Gbit/in(2) magnetic recording. In th e presence of demagnetizing field, a single layer film has little ther mal effect at the upper limit of the projected grain sizes, while ther mal decay is obvious when grain sizes are at the lower limit. The magn itude 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 ten ds to demagnetize the film, therefore making the thermal effect worse. The thermal decay in multilayer media tends to cancel the gain in noi se reduction obtained by dividing the film layer at ultrahigh recordin g density. The effects of magnetostatic and exchange interaction, anis otropy, and grain volume on thermal stability are discussed.