Morphology and magnetic properties of Pt/Co/Pt sandwiches grown by argon sputter deposition

The magnetic properties of Pt/Co/Pt sandwiches prepared by sputtering onto Al-2-O-3 (0 0 0 1) single crystal substrates have been investigated in relation with their structure. Co island coalescence is completed before deposition of 40 Angstrom of Pt. The structural properties-roughness, texture, grain size-are optimized for substrate temperature near 600degreesC (300degreesC respectively) during Pt (Co resp.) deposition, and Pt buffer layer thickness of 40 Angstrom. Under these conditions, the magnetic properties can be largely accounted for by the abruptness of the Co/Pt interfaces. For cobalt layers thinner than 20 Angstrom, the magneto-crystalline anisotropy is strong enough to overcome the shape anisotropy, so that the easy axis of magnetization is out-of-plane. Magnetization reversal process was investigated by magneto-optical magnetometry and microscopy. Our results indicate that the magnetization reversal mechanism involves very few nucleation events followed by fast domain wall motion, through the sample. The characteristics lengths involved in the domain wall motion are derived and discussed. (C) 2002 Elsevier Science B.V. All rights reserved.