Novel vertically aligned nanocomposite of Bi₂WO₆-Co₃O₄ with room-temperature multiferroic and anisotropic optical response

A new vertically aligned nanocomposite (VAN) structure based on two-dimensional (2D) layered oxides has been designed and self-assembled on both LaAlO₃ (001) and SrTiO₃ (001) substrates. The new VAN structure consists of epitaxially grown Co₃O₄ nanopillars embedded in the Bi₂WO₆ matrix with a unique 2D layered structure, as evidenced by the microstructural analysis. Physical property measurements show that the new Bi₂WO₆-Co₃O₄ VAN structure exhibits strong ferromagnetic and piezoelectric response at room temperature as well as anisotropic permittivity response. This work demonstrates a new approach in processing multifunctional VANs structure based on the layered oxide systems towards future nonlinear optics, ferromagnets, and multiferroics.