Thermomagnetic direct overwrite in TbFe using thermally induced domain wall energy gradient

Abstract

A method is described for thermomagnetic direct overwrite in amorphous Tb23 Fe77. Using long (500 ns) laser pulses, micron-size domains can be written with diameters significantly smaller than the diameter of the Curie temperature isotherm. The relatively small domain size is due to the collapsing effect of the thermally generated domain wall energy gradient. Without switching the magnetic bias field, the domains can be collapsed to submicron size using short (50 ns) laser pulses. Domains can be completely erased by firing short pulses in succession as the recording medium is moved slowly with respect to the optical beam.