Magnetic force microscopy on cobalt nanocluster films

Magnetic force microscopy (MFM) has been employed to image the magnetic stray field from cobalt nanocluster films. The uniformly sized clusters with a diameter about 10 nm were deposited at low energy with a gas aggregation source. Both isolated particles supported on silicon, and cluster-assembled films were analyzed. MFM measurements on individual clusters are complicated by interference from surface height variations, while for thicker layers a clear field pattern can be observed. The magnetic correlation length across such films is substantially larger than the size of a single cluster, indicating that the clusters are magnetically coupled to form stable domains. In ex situ magnetization experiments, a small increase or decrease in the MFM phase signal occurred depending on the direction of the applied field. # 2003 Elsevier B.V. All rights reserved