Magnetostructural correlations in BiFeO3-based multiferroics

Inspired by the potential applications of the magnetoelectric effect, interest in multiferroic materials is growing steadily. While BiFeO 3 is the most thoroughly studied magnetic ferroelectric compound, the properties of its solid solutions remain a matter of intensive debate. In this paper we show how variation in the chemical composition of Bi 1− x Ae x Fe 1− x Ti x O 3 (Ae = Ca, Sr, Ba) perovskites affects their crystal structure and magnetic behavior. In particular, our research demonstrates that Ca/Ti and Sr/Ti substitutions suppress the cycloidal antiferromagnetic structure specific to the parent compound, thus stabilizing a weak ferromagnetic ferroelectric state. The Ba/Ti-doped solid solutions retain the magnetic behavior characteristic of the pure BiFeO 3 . Since the latter observation is directly opposed to the prevailing concept used in describing magnetic phenomena in the Bi 1− x Ba x Fe 1− x Ti x O 3 series, the origin of the contradiction between the current and previously reported data is analyzed. Finally, the reasons underlying the difference in the magnetic properties of the Bi 1− x Ae x Fe 1− x Ti x O 3 compounds are discussed. The reasons behind the composition- and magnetic field-driven instability of the cycloidal antiferromagnetic order in the polar phase of bismuth ferrites are analyzed.