The preparation, and structural and multiferroic properties of B-site ordered double-perovskite Bi2FeMnO6

Abstract

We report the structural, magnetic, and ferroelectric properties of double-perovskite Bi2FeMnO6 in which Fe3+ and Mn3+ cations are present with alternative ordering along the [111] direction. High-flux synchrotron X-ray diffraction and high resolution transmission electron microscopy show that the pseudo-cubic lattice of Bi2FeMnO6 consists of alternatively corner-shared octahedra of FeO6 and MnO6. In the highly ordered Bi2FeMnO6 thin films, the unusual spin-glassy magnetic state is observed below 18 K by a superconducting quantum interference device, and this is ascribed to the magnetic frustration at the [111] Fe3+ and Mn3+ planes as indicated by X-ray magnetic circular dichroism measurements. Combining with the orbital model analysis based on Goodenough-Kanamori-Anderson rules, first-principles calculations and Monte Carlo simulations suggest that magnetic frustration is dominated by the long-range second nearest neighboring antiferromagnetic interactions of Fe3+-Fe3+ and Mn3+-Mn3+ and leads to the surprisingly weak magnetism. On the other hand, robust room-temperature ferroelectricity in Bi2FeMnO6 films is confirmed by piezoelectric force microscopy through electrically switching the polarization state and the ferroelectric retention.