Growth of InFeCoO4 thin films on SrTiO3 and MgO substrates

We have studied the effect of deposition conditions and strain on the phase stability, grain structure, grain orientation, crystallinity, and magnetism of InFeCoO4 spinel thin films grown on single-crystal (0 0 1) SrTiO3 (STO) and (0 0 1) MgO substrates. The growth window for good-quality films exhibiting uniform orientation was observed to be very narrow with deviations from optimal conditions resulting in highly disordered growth characterized by mixed (0 0 1) and (1 1 1) type orientations, expanded out-of-plane lattice constants, and reduced symmetry for the (0 0 1) oriented grains. Bulk-like magnetic properties could be obtained in films grown on STO under optimal conditions, whereas significantly lower values for saturation magnetization and T-C were observed for the disordered samples. The absence of frequency-dependent components in AC-magnetization measurements indicates the absence of a glassy state previously observed in bulk InFeCoO4. The significantly smaller grain size of the samples grown on MgO at optimal conditions resulted in depressed T-C in addition to a strong superparamagnetic effect below 20 K. (C) 2010 Elsevier B.V. All rights reserved.