Ferromagnetism and magnetodielectric effect in insulating LaBiMn4/3Co2/3O6 thin films

High quality epitaxial thin films of LaBiMn4/3Co2/3O6 perovskite were fabricated on (001)-oriented SrTiO3 and LaAlO3 substrates by the pulsed laser deposition technique. Magnetization measurements reveal a strong magnetic anisotropy and a ferromagnetic behavior that is in agreement with a superexchange interaction between Mn4+ and Co2+ ions, which are randomly distributed in the B site. A distinct anomaly is observed in the dielectric measurements at 130 K corresponding to the onset of the magnetic ordering, suggesting a coupling. Above this temperature, the extrinsic Maxwell-Wagner effect is dominating. These results are explained using the Raman spectroscopic studies indicating a weak spin-lattice interaction around this magnetic transition. (C) 2008 American Institute of Physics.