Pulsed laser deposition of cobalt ferrite in a reactive O2:N2 atmosphere: effect of the deposition pressure and temperature

Thin films of CoFe2O4 have been fabricated by pulsed laser ablation of a metallic CoFe2 target at two different temperatures (200 and 400 °C) and in various O2:N2, 20:80 pressures [from 0.7 Pa (5×10-3 Torr) up to 26.7 Pa (2×10-1 Torr)]. Too low pressures resulted in an insufficient oxidation of the deposited material and an antiferromagnetic (Fe,Co)O phase is observed together with CoFe2O4. A minimum pressure of 6.7 Pa was found necessary to obtain pure CoFe2O4 films with magnetic properties close to the bulk. The higher the pressure and the temperature, the larger was the roughness of the films. The optimum deposition temperature and pressure to obtain flat (3 nm rms roughness) CoFe2O4 films were, respectively, 200 °C and 6.7 Pa.