Tailoring the structural and magnetic properties of masked CoPt thin films using ion implantation

摘要

The effects of ion implantations through a mask on the structural and magnetic properties of Cosub80/subPtsub20/sub films were investigated. The mask was patterned using the self-assembly of diblock copolymers. For implantation, high (40 keV for sup14/supNsup+/sup and 100 keV for sup40/supArsup+/sup) and low (7.5 keV for sup14/supNsup+/sup and 4.5 keV for sup40/supArsup+/sup) energy sup14/supNsup+/sup and sup40/supArsup+/sup ions were used to modify the structural and magnetic properties of these films. X-ray diffraction and TRIM simulations were performed for understanding the structural changes due to ion implantations. These results revealed the intermixing of Co atoms in lower layers and lattice expansion in Cosub80/subPtsub20/sub magnetic and Ru layers. A lateral straggling of Co caused an increase in the exchange coupling in the masked region. Depletion of Co atoms in Cosub80/subPtsub20/sub layer caused a decrease in the anisotropy constant, which were further confirmed by the alternating gradient force magnetometer and magnetic force microscopy results. The magnetic force microscopy images showed an increase in domain width and domain wall width confirming the above-mentioned effects.