Domain formation characteristics during thermomagnetic recording for amorphous TbFe and TbFeCo alloy thin films

The configurational characteristics of thermomagnetically written domains under a static laser irradiation condition were observed by using a polarizing microscope. The shapes of the domains were categorized into three distinctly different types: (1) circular domains with size almost independent of the applied field, (2) domains growing in size and assuming smoother boundaries with increasing applied field, and (3) domains unrecordable at any condition. It was confirmed that the domain configurations were determined mainly by which one was the dominant controlling factor between demagnetizing and domain wall energy at elevated temperatures in the thermomagnetic recording process. The bit shape irregularity found in some alloys of TbFe was attributed to nonuniformity in magnetic properties inherent in the amorphous structure