Synthesis of nanoscale composites of exchange biased MnFe2O4 and Mn-doped BiFeO3

Abstract

Exchange bias may be used to couple a normal ferromagnet to a ferroelectric antiferromagnet and thus create a multiferroic system with nonzero magnetization. In implementing this idea the authors developed a synthesis method for composite films of nanoscale clusters of ferromagnetic MnFe2O4 embedded in multiferroic Mn-doped BiFeO3. The method utilizes the Bi volatility to obtain the composite films via thermal annealing of multilayers composed of BiFeO3 and BiMnO3. The cluster size varies from 20 to 80 nm depending on the film thickness. The composite films possess both ferroelectric and ferromagnetic properties; the magnetic hysteresis curves, in particular, manifest exchange bias. (c) 2007 American Institute of Physics.