Effects of ion implantation on magnetic and structural properties of amorphous Gd-Co thin films

An experimental study of the structural and magnetic properties of noncrystalline Gd-Co thin films before and after ion implantation has been carried out. The samples have been obtained by a modified RF cosputtering method in a diode-type apparatus. The energy used in implantation was 40 keV with total fluences of 1*10¹⁶ and 5*10¹⁶ Ar atoms cm^-2. Rutherford backscattering spectrometry, X-ray, and EDAX techniques have been used for structural analysis. The magnetic domain structure, local hysteresis loops, and coercive forces on the implanted and unimplanted samples were studied using magnetooptic polar Kerr effect (MO) with a metallographic polarizing microscope. The structural measurements pointed to the Gd-Co films being completely amorphous before and after Ar implantation. The MO measurements showed a decrease of magnetic domain width, a progressive diminution of the local hysteresis loop area and an increase of the absolute value of coercive forces for all samples, with increasing doses.