Multiferroic Compounds with Double-Perovskite Structures

New multiferroic compounds with double-perovskite structures were synthesized. Bi(2)NiMnO(6) was synthesized in bulk form by high-pressure synthesis and also in a thin-film form by epitaxial growth. The material showed both ferromagnetic and ferroelectric properties, i.e., the multiferroic property at low temperature. Bi(2)FeCrO(6) was also fabricated in a (1 1 1) oriented BiFeO(3)/BiCrO(3) artificial superlattice, with a 1/1 stacking period. The superlattice film showed ferromagnetic behavior and polarization switching at room temperature. In the compounds, Bi(3+) ion, located at the A site in the perovskite structure, caused ferroelectric structural distortion, and the B-site ordering of the Ni(2+) and Mn(4+) ions (Fe(3+) and Cr(3+) ions) in a rock-salt configuration led to ferromagnetism according to the Kanamori-Goodenough rule.