Cation-, dipole-, and spin-order in perovskite oxides.

Single phase compounds based on the Pb(Fe$_{2/3}$W$_{1/3})$O$_{3}$ perovskite oxide were designed and synthesized to develop long range cation order on the B-site in the ABO$_{3}$ structure. Pure Pb(Fe$_{2/3}$W$_{1/3})$O$_{3}$ oxide displays 1:1 cation order and electric dipole order both at only the nanometer scale. As a consequence of the nanoscale polar order, it shows a relaxor ferroelectric behavior with zero remanent polarization. Chemical doping schemes were designed to develop long range cation order. Presumably a long range polar order will accompany the long range cation order. Therefore, a normal ferroelectric behavior with some remanent polarization is expected. Since perovskite oxide structure favors the G-type antiferromagnetic order, an uncompensated antiferromagnetic order is also expected since the different occupancy of the Fe$^{3+}$ on the two B-site sublattices. As a consequence, this will lead to an oxide with net magnetization. In this experimental study, the Pb(Fe$_{2/3}$W$_{1/3})$O$_{3}$ perovskite oxide was chemically modified with Zn-, Sc-, and In-dopants. Long rang B-site cation order was successfully developed. Ferroelectric and magnetic properties measurements have shown that these double-perovskite compounds are promising magnetoelectric multiferroic materials.