Experimental studies were performed on model bilayers of fully ordered L1(0
) CoPt with thicknesses of 25, 50, or 100 nm, capped by Co of varying thick
nesses from 2.6-75 nm. The bilayers were subjected to different annealing c
onditions; transmission electron microscopy and x-ray diffraction supplied
data concerning the crystallographic structure, microstructure, and texture
of the constituent phases in the bilayers. The degree of exchange coupling
was investigated primarily with magnetic measurement and magnetic force mi
croscopy. Samples subjected to annealing treatments at 300 degreesC showed
evidence of grain growth and increased texture of the hexagonally close-pac
ked (hcp) cobalt layer relative to the as-deposited condition. The degree o
f exchange coupling in these materials improved only slightly with annealin
g, as evidenced by both magnetic recoil curve measurement and magnetic forc
e microscopy. Samples subjected to a higher-temperature annealing treatment
of 550 degreesC evidenced dramatic improvement in the magnetic coupling, a
n improvement attributed to interdiffusion of CoPt and Co and the formation
of alloy phases, specifically face-centered-cubic and hcp Co-Pt solid solu
tions. (C) 2001 American Institute of Physics.