High coercivity and magnetic domain observation in epitaxially grown particulate FePt thin films

We have investigated the magnetic domains of high coercive FePt[001]/MgO[001] films with various morphologies by magnetic force microscopy (MFM). The film morphology changes from particulate to continuous depending on the film thickness (t), accompanied by a drastic decrease in coercivity when t exceeds the critical thickness, t(c) = 45 nm. The film with t = 10 nm is comprised of only single-domain particles of approximately 50 nm, which has a huge coercivity as high as 40 kOe. The isolated particles larger than 200 nm, are multi-domain, and the films containing these isolated particles show slightly lower coercivity. The coercivity drastically decreases with the percolation of the particles. (C) 2003 Elsevier B.V. All rights reserved.