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Nanoelectronic devices integrated with functional complex oxides have drawn much attention in recent years. However, due to material and processing compatibility issues, integrating functional complex oxides with Si-based devices is challenging, and success has been limited. As an example, the Bi3Fe2Mn2Ox(BFMO) supercell system, a single-phase layered oxide made by compositing BiFeO3and BiMnO3, has been studied for much of the past decade for its unusual layered Aurivillius structure and magnetic and ferroelectric properties. However, most of the BFMO thin film growth has been demonstrated on single-crystal oxide substrates such as SrTiO3and LaAlO3. In this work, we demonstrate that the BFMO layered supercell phase can be integrated on Si with high epitaxial quality using a buffer stack of TiN/SrTiO3/CeO2. Further understanding of the strain-controlled growth of the BFMO supercell phase has allowed such Si integration. Microstructure, magnetic, ferroelectric, and optical properties of the BFMO films on Si have been characterized and compared with those of BFMO on SrTiO3single-crystal substrates, demonstrating comparable epitaxial quality and physical properties. Integrating multiferroic BFMO oxides on Si demonstrates the potential of layered supercell oxides in practical device applications such as ferroelectric field effect transistors.

Integrating functional thin films with anisotropic physical properties onto flexible substrates is of great interest for future flexible electronic applications. In this work, self-assembled BaZrO3(BZO)-Co vertically aligned nanocomposite thin films have been integrated onto flexible mica substrates using pulsed laser deposition. Microstructure characterization shows high-quality growth of Co nanopillars in the BZO matrix. Tunable, anisotropic ferromagnetic properties of the films have been achieved by controlling the film thickness and the aspect ratio of Co nanopillars. The bending stability tests have been carried out under different bending conditions and cyclic bending conditions to explore the physical property variation of the films. The successful integration of BZO-Co on mica substrates opens a way for future flexible spintronics and device integration.

Materials with magneto-optic coupling properties are highly coveted for their potential applications ranging from spintronics and optical switches to sensors. In this work, a new, three-phase Au–Fe–La0.5Sr0.5FeO3(LSFO) hybrid material grown in a vertically aligned nanocomposite (VAN) form has been demonstrated. This three-phase hybrid material combines the strong ferromagnetic properties of Fe and the strong plasmonic properties of Au and the dielectric nature of the LSFO matrix. More interestingly, the immiscible Au and Fe phases form Au-encapsulated Fe nanopillars, embedded in the LSFO matrix. Multifunctionalities including anisotropic optical dielectric properties, plasmonic properties, magnetic anisotropy, and room-temperature magneto-optic Kerr effect coupling are demonstrated. The single-step growth method to grow the immiscible two-metal nanostructures (i.e., Au and Fe) in the complex hybrid material form opens exciting new potential opportunities for future three-phase VAN systems with more versatile metal selections.

Silicon integration of nanoscale metamaterials is a crucial step toward low-cost and scalable optical-based integrated circuits. Here, a self-assembled epitaxial Au–BaTiO3(Au–BTO) hybrid metamaterial with highly anisotropic optical properties has been integrated on Si substrates. A thin buffer layer stack (<20 nm) of TiN and SrTiO3(STO) was applied on Si substrates to ensure the epitaxial growth of the Au–BTO hybrid films. Detailed phase composition and microstructural analyses show excellent crystallinity and epitaxial quality of the Au–BTO films. By varying the film growth conditions, the density and dimension of the Au nanopillars can be tuned effectively, leading to highly tailorable optical properties including tunable localized surface plasmon resonance (LSPR) peak and hyperbolic dispersion shift in the visible and near-infrared regimes. The work highlights the feasibility of integrating epitaxial hybrid oxide–metal plasmonic metamaterials on Si toward future complex Si-based integrated photonics.