Antiferroelectricity in multiferroic BiCr O3 epitaxial films

Multiferroic BiCr O3 epitaxial films were grown by pulsed laser deposition on SrTi O3 (001) substrates with SrRu O3 bottom electrodes. The authors found that the films exhibit antiferroelectricity with a characteristic electric field induced ferroelectric phase, as evidenced by double hysteretic behaviors in the electric field dependence of dielectric constants and polarization. The antiferroelectricity is consistent with theoretical predictions that the Bi lone pair induces polarization in bismuth-based perovskites, such as ferroelectric BiMn O3 and BiFe O3. Magnetic measurements revealed weak parasitic ferromagnetism resulting from antiferromagnetic ordering below 140 K. This magnetic transition coincides with a local maximum in the dielectric constants' temperature dependence.