Magnetic properties of Co/Pt multilayers on self-assembled particle arrays

A series of [Co(x)/Pt(0.8 nm)](8) multilayers with varying individual Co layer thickness was deposited onto self-assembled particle monolayers with particle sizes as small as 58 nm forming arrays of magnetic nanostructures. A maximal out-of-plane coercivity was observed for a Co layer thickness of 0.3 nm for all particle sizes, which decreases with further increasing Co layer thickness indicating a transition of the easy axis orientation from perpendicular to the film plane at about 0.8 nm Co layer thickness. While a single-domain state is the most favorable state after perpendicular demagnetization for a Co layer thickness of up to 0.4 nm for all particle sizes, greater Co layer thicknesses reveal a multidomain state. In addition, the angle dependent magnetization reversal behavior and the domain configurations of these magnetic nanostructures were investigated systematically. At the crossover thickness of 0.4 nm Co layer thickness, a two-domain configuration can be induced for 320 nm particles by applying a magnetic field under a critical angle of 75 degrees. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.3003064]