Effect of deposition temperature on structural, microstructural and magnetic properties of CoFe₂O₄ thin films deposited by pulsed laser deposition

A systematic study about the variation in microstructure and magnetic properties of Cobalt ferrite thin films, deposited on Si/SiO₂/TiO₂/Pt (111) substrate by using pulsed laser deposition at a constant oxygen pressure of 9 Pa with substrate temperatures ranging from 550 to 750 °C at an interval of 100 °C has been reported. All films showed the (111) preferred orientation with single phase confirmed by grazing incidence X-ray diffraction and Raman spectra. Moreover, the films showed all the active raman modes that were present in the cobalt ferrite target. The films deposited at 550 and 650 °C exhibits uniform and smooth surface features whereas deposition at 750 °C gives rise to porosities and voids due to re-evaporation of atoms from the deposited film. The grain size and roughness of the films increased with increasing deposition temperature. The induced in-plane tension in the film due to thermal expansion mismatch between substrate and film causes the increase in the perpendicular magnetic anisotropy. A sharp increase in out-of-plane coercivity and the domain size was observed at higher deposition temperatures.