X-ray and neutron scattering studies of laser-annealed TbFeCo thin films

Rare earth-transition metal alloy thin films are currently the primary media for magnetooptic data storage. Although they possess very good magnetic properties they also have several undesirable qualities. In order to enhance their performance we have concentrated on attempting to allow the as-sputtered film structure to relax by use of pulsed laser beam irradiation. This technique has several advantages over thermal annealing, in particular the ability to tune the laser wavelength to a region which is absorbing in only one layer of the disc, in order to confine the effects of the anneal to that layer. By tuning a laser to an absorbing wavelength in TbFeCo media we have been able to produce local transient temperatures approaching 3000 °C, modifying the magnetic behaviour of the samples yet without significantly affecting their macroscopic layer structure. The structure has been probed by use of neutron and X-ray reflectivity measurements. In analysing the structure of samples which had corroded severely in the atmosphere, we have shown the power of complementary neutron and X-ray techniques to remove some of the ambiguity often present in the analysis of data from one of the techniques alone.