The multiferroic properties of BiFe0.5Mn0.5O3 and BiFeO3/BiMnO3 superlattice films

BiFe0.5Mn0.5O3 (BFMO) and BiFeO3/BiMnO3 superlattice (BFO/BMO) films were epitaxially grown on (111) SrTiO3 substrates by pulsed laser deposition. The ferroelectricity of both BFMO and BFO/BMO has been confirmed by piezoresponse force microscopy. Weak ferromagnetism was observed for both samples. The magnetization of BFO/BMO is smaller than that of BFMO, confirming the antiferromagnetic Fe3+-O2--Mn3+ interaction. Two anomalies at low temperature, T-1 = 235K and T-2 = 42K for BFMO and T-1 = 198K and T-2 = 77K for BFO/BMO, were observed in temperature dependent magnetization (M-T) curves. The peaks at T-1 in zero field cooled (ZFC) M-T curves for both samples can be understood by the onset of Fe3+-O2--Mn3+ interaction. The peak at T-2 for BFMO can be understood by the blocking of ferromagnetic Mn-rich clusters due to the inhomogeneous distribution of Mn. The peak at T-2 for BFO/BMO observed in both field cooled and ZFC M-T curves has been ascribed to the enhanced single-ion magnetocrystalline anisotropy due to the highly distorted oxygen octahedra in the ordered structure of Fe3+ and Mn3+ ions along (111) orientation. (C) 2015 AIP Publishing LLC.