A robust approach for the growth of epitaxial spinel ferrite films

Heteroepitaxial spinel ferrites NiFe(2)O(4) and CoFe(2)O(4) films have been prepared by pulsed laser deposition at various temperatures (175-690 degrees C) under ozone/oxygen pressure of 10 mTorr. Due to enhanced kinetic energy of ablated species at low pressure and enhanced oxidation power of ozone, epitaxy has been achieved at significantly lower temperatures than previously reported. Films grown at temperature below 550 degrees C show a novel growth mode, which we term vertical step-flow growth mode. Epitaxial spinel ferrite films with atomically flat surface over large areas and enhanced magnetic moment can be routinely obtained. Interestingly, the growth mode is independent of the nature of substrate (spinel MgAl(2)O(4), perovskite SrTiO(3), and rock-salt MgO) and film thickness. The underlying growth mechanism is discussed. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3488638]