Pulsed Laser Deposition Films from a BaFeMoO Target Onto SrTiO[001]: Chemical and Magnetic Inhomogeneity

Pulsed laser deposition films from BaFeMoO (BFMO) targets onto SrTiO[001] (STO) substrates have been reported previously to have non-zero magnetism at 300 K, a majority of magnetic ordering at 240 K that is less than the 370 K ordering temperature of polycrystalline BFMO, and suppressed saturation magnetization compared to polycrystalline BFMO. To interrogate these previously reported observations of BFMO on STO, we have used a combination of x-ray diffraction, atomic force microscopy, x-ray and neutron reflectivity, and x-ray photoelectron spectroscopy that shows inhomogeneities. The present results show off-stoichiometry on the A-site by incorporation of Sr from the substrate and on the B-site to have %Fe/%Mo > 1 by evolution of BaMoO. There is an enhanced ordering temperature and magnetic response nearer to the SrTiO interface compared to the air interface. Depth dependent strain and microstructure are needed to explain the magnetic response. Holistic considerations and implications are also discussed.