Effect of spacer layer thickness on magnetic interactions in self-assembled single domain iron nanoparticles

The magnetic characteristics of iron nanoparticles embedded in an alumina thin film matrix have been studied as a function of spacer layer thickness. Alumina as well as iron nanoparticles were deposited in a multilayered geometry using sequential pulsed laser deposition. The role of spacer layer thickness was investigated by making layered thin film composites with three different spacer layer thicknesses (6, 12, and 18 nm) with fixed iron particle size of similar to 13 nm. Intralayer magnetic interactions being the same in each sample, the variation in coercivity and saturation magnetization is attributed to thickness dependent interlayer magnetic interactions of three types: exchange, strong dipolar, and weak dipolar. A thin film composite multilayer structure offers a continuously tunable strength of interparticle dipole-dipole interaction and is thus well suited for studies of the influence of interaction on the magnetic properties of small magnetic particle systems.