The effect of deposition process on the magnetic properties of coupled permalloy thin films

Abstract

Double layer thin films of permalloy (layer thickness 200-1300 A) with tantalum (50 A) as a nonmagnetic spacer have been prepared by e-beam evaporation. The effec.t of deposition parameters, especially the substrate temperature on the magnetic properties of these films has been examined. The coercivity(I&) of the double layer films was found to be very sensitive to the substrate temperature in the permalloy layer thickness range of 200-600 A. The coercivity of the films deposited at 40 "C is lower than at 300 "C and is almost independent of the Permalloy layer thickness. The XRD patterns and STM images of these two films exhibit large differences in permalloy grain size and grain orientation. However, the He of the single layer films deposited nnder the same conditions as the double layer films shows no significant change in this thickness region. The results indicate that the change of interface condition is primarily responsible for the Ifc variation in the coupled films deposited at different substrate temperatures and strongly suggest t.hat interface roughness plays a dominant role in the coupling between the permalloy layers.