Measurement of transient temperature during thermomagnetic writing in MO recording media

Real-time Kerr contrast images produced by a time-resolved microscope were used to derive transient temperature during thermomagnetic (TM) writing. Temperature profiles in magnetooptical films during TM writing were measured, and Curie diameter could be derived. With 5-ns and 0.3-μm temporal and spatial resolutions, one could determine transient temperature during both heating and cooling cycles in TM writing with adequate resolutions. Since thermal parameters such as heat conductivity K, and specific heat C of thin films are difficult to measure accurately, the numerical analyses tend to fit C, K, and others to match reasonable transient temperature profiles. With the developed techniques, a more reliable way to determine the outcome of a TM writing is thus feasible. Moreover, these methods, in conjunction with numerical methods, can be used to derive more realistic values of the thermal parameters of material in thin-film form