Role of the Epitaxy Relations in the CoCrPt Thin Films with Bilayer V/Cr Underlayers

ABSTRACTThe effects of grain-to-grain epitaxy conditions on the magnetic properties of high coercivity CoCr13Pt13 films with bilayer Cr/Cr, V/Cr and V/V underlayers were studied. V/Cr films were used in order to obtain underlayers that would differ from Cr only by a size of the lattice constant. Introduction of V instead of Cr as an underlayer changed the relative misfits between CoCrPt and the underlayer lattice and increased the amount of {0002} texture in the magnetic film. This effect led to a decrease in the in-plane coercivity. CoCrPt/V/Cr and CoCrPt/Cr/Cr films exhibited similar texture of the underlayer, the same microstructure and similar level of internal stress. Correspondingly the decrease in coercivity did not exceed 10% (from 2.7 kOe to 2.5 kOe). On the other hand CoCrPt/V/V film had more than 4 times smaller coercivity (0.6 kOe). In this case, change in the magnetic properties was caused not only by altered misfits but also by the change in microstructure, texture and state of stress in the film. Results obtained indicate that small changes in misfits between a magnetic layer and an underlayer can be effectively used to control coercivity only if other structural parameters remain unchanged.