Structural and magnetic properties of laser-annealed magneto-optic thin films

In order to enhance the performance of rare-earth-transition-metal thin films, an attempt has been made to allow the as-sputtered film structure to relax by use of pulsed laser beam irradiation. This technique has several advantages over other forms of annealing, in particular the ability to tune the laser wavelength to a region which is absorbing in only one layer of the disk, 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 it was possible to produce local transient temperatures up to 3000°C, modifying the magnetic behavior of the samples without significantly affecting their macroscopic layer structure. Anneals to a temperature of about 690°C were found to introduce an additional soft magnetic component to the hysteresis loop, doubling the values of both the saturation and the remanent magnetization. On the other hand, anneals near 3000°C destroyed the perpendicular anisotropy. The structure has been probed by neutron and X-ray reflectivity measurements, and the magnetic properties have been studied by vibrating sample magnetometry