Composition-driven magnetic and structural phase transitions in Bi1-xPrxFe1-xMnxO3 multiferroics.

Magnetic ferroelectrics continue to attract much attention as promising multifunctional materials. Among them, BiFeO3 is distinguished by exceptionally high transition temperatures and, thus, is considered as a prototype room-temperature multiferroic. Since its properties are known to be strongly affected by chemical substitution, recognition of the doping-related factors determining the multiferroic behavior of the material would pave the way towards designing the structures with enhanced magnetoelectric functionality. In this paper, we report on the crystal structure and magnetic and local ferroelectric properties of the Bi1-xPrxFe1xMnxO3 (x≤ 0.3) compounds prepared by a solid state reaction method. The polar R3c structure specific to the parent BiFeO3 has been found to be unstable with respect to doping for x...0.1. Depending on the Pr/Mn concentration, either the antipolar PbZrO3-like or nonpolar PrMnO3-type structure can be observed. It has been shown that the non-ferroelectric compounds are weak ferromagnetic with the remanent/spontaneous magnetization linearly decreasing with an increase in x. The samples containing the polar R3c phase exhibit a mixed antiferromagnetic/weak ferromagnetic behavior. The origin of the magnetic phase separation taking place in the ferroelectric phase is discussed as related to the local, doping introduced structural heterogeneity contributing to the suppression of the cycloidal antiferromagnetic ordering characteristic of the pure BiFeO3. [ABSTRACT FROM AUTHOR]