Optical, ferroelectric and magnetic properties of multiferroelectric BiFeO3-(K0.5Na0.5)0.4(Sr0.6Ba0.4)0.8Nb2O6 thin films

Multiferroic BiFeO3-(K0.5Na0.5)0.4(Sr0.6Ba0.4)0.8Nb2O6 (BFO-KNSBN) trilayer thin films, were epitaxially grown on MgO(0 0 1) and SrTiO3(0 0 1) by using pulsed laser deposition (PLD). Their ferroelectric, magnetic, dielectric and optical properties were investigated. It was found that both ferroelectric polarization and dielectric constant of the films were enhanced by introducing KNSBN as a barrier layer. Meanwhile, ferromagnetism of BFO was maintained. More interestingly, a double hysteresis magnetic loop was observed in the KNSBN-BFO-KNSBN trilayer films, where exchange bias and secondary phase in the BFO layer played crucial roles. Interactions between adjacent layers were revealed by temperature-dependent Raman spectroscopic measurements.