Magnetic Properties of CoFe2O4 Nanopillars*

Ferrimagnetic CoFe$_{2}$O$_{4}$ spontaneously forms nanopillars embedded in a BaTiO$_{3}$ or BiFeO$_{3}$ matrix during thin film growth by pulsed laser deposition. Such thin film nanostructures show three dimensional heteroepitaxy. All the films have a large uniaxial magnetic anisotropy with an easy axis normal to the film plane. It is calculated that stress anisotropy is the main contribution to the anisotropy field. We studied the magnetic behavior of the CoFe$_{2}$O$_{4}$ nanopillars formed at different growth temperatures, with different film thickness and on various substrates.