Effect of the thermal interference in thermomagnetically recorded domains

The dependence of the thermal interference among thermomagnetically recorded domains on various layer structures is investigated by numerical simulations of the laser-induced heat flow. A trilayer structure with a Ta₂O₅ overcoat and undercoat has low thermal diffusivity and therefore a slow thermal response. Accordingly, peak positions of the isothermal contours are dragged backward toward the prior pulse due to the thermal interference. This thermal dragging effect is evidently prevented by applying an Al topcoat. The calculated results are verified by peak interval measurements. For high-density recording, the application of a heat sink layer is recommended to avoid the influence of the thermal dragging of the recorded domains during optically modulated pulse recording