Two-Phase Room-Temperature Multiferroic Nanocomposite with BiMnO₃-Tilted Nanopillars in the Bi₂W_1-MnO₆ Matrix

Single-phase multiferroics are scarce because of the fact that the coexistence of magnetism (spin order) and ferroelectricity (electric dipole order) in a single-phase material may be limited. Taking advantage of the nanocomposite design, combining a ferroelectric phase and a ferromagnetic phase presents enormous opportunities in multiferroic material exploration. In this work, a new 2D-layered framework of Bi₂W_1-MnO₆-BiMnO₃ (BWMO-BMO) in the nanocomposite thin-film form has been demonstrated and shows obvious room-temperature multiferroic properties, that is, ferroelectric and ferromagnetic at room temperature. The BMO phase forms a unique tilted domain structure in the BWMO matrix, and both phases are of excellent epitaxial quality. The ferroelectric response originates from the layered Aurivillius phase of the BWMO matrix, and the ferromagnetic properties mainly arise from the BMO nanodomains. Moreover, the band gap of the BWMO-BMO nanocomposite is effectively tuned to 3.10 eV from its original 3.75 eV of BWO. This study demonstrates a new design of nanocomposite using layered oxides toward future multifunctional oxides for nanoscale devices.