spintronics, [2] multiferroics, [3] and quantum systems. [4] Several two-phase nanocomposite systems, exhibiting multilayer or nanowire morphology, have been demonstrated for achieving enhanced physical properties, including ferroelectricity, [5] ferromagnetism, [6] magnetoresistance, [7] and exotic optical properties such as optical magnetism, [8] negative refraction, [9] and hyperbolic dispersion. [10] For example, hyperbolic metamaterials with ordered and anisotropic metal-dielectric nanocomposite designs support the propagation of high wavevectors. [11] Since very few hyperbolic materials exist naturally, this artificially engineered nanocomposite approach provides a multifunctional platform to realize such materials with applications in subdiffraction imaging, [12] sensing, [13] waveguiding, [14] and also offers an opportunity to achieve coupled electric, magnetic, and optical responses. However, due to the availability of a limited range of structures in terms of crystallinity and morphology, a greater design flexibility and a structural complexity along with versatile growth techniques are needed for developing next generation integrated photonic and electronic devices. This can be achieved by incorporating a third phase through the three-phase nanocomposite designs by judicious selection of materials and functionalities.Besides material selection, the spatial ordering of the phases has great impacts on the overall functionalities of nanocomposite materials. Previous efforts to grow ordered ceramicmetal nanocomposites have focused on applying patterning techniques such as anodized alumina oxide (AAO) templates, [15] e-beam lithography, [16] focused ion beam (FIB), [17] and substrate nanotemplate. [18] In contrast, a self-assembly approach for fabricating such ordered oxide-metal nanocomposites is costeffective and overcomes the resolution limitation and complex fabrication steps. Controlled synthesis of such self-assembled complex hybrid nanostructures with desired ordering and epitaxial quality remains a challenge. Specifically, large difference in surface energy, growth kinetics, and high tendency of oxidation and interdiffusion between vastly different phases remains as a major challenge and imposes difficulties in ordering control. Despite the recent success of the self-assembled epitaxial Complex multiphase nanocomposite designs present enormous opportunities for developing next-generation integrated photonic and electronic devices. Here, a unique three-phase nanostructure combining a ferroelectric BaTiO 3 , a wide-bandgap semiconductor of ZnO, and a plasmonic metal of Au toward multifunctionalities is demonstrated. By a novel two-step templated growth, a highly ordered Au-BaTiO 3 -ZnO nanocomposite in a unique "nanoman"-like form, i.e., self-assembled ZnO nanopillars and Au nanopillars in a BaTiO 3 matrix, is realized, and is very different from the random three-phase ones with randomly arranged Au nanoparticles and ZnO nanopillars in the BaTiO 3 matrix. The ordered three-phase "nanoman"-like structu...

Vanadium dioxide (VO) thin films with controlled thicknesses are deposited on c-cut sapphire substrates with Al-doped ZnO (AZO) buffer layers by pulsed laser deposition. The surface roughness of AZO buffer layers is varied by controlling oxygen pressure during growth. The strain in the VO lattice is found to be dependent on the VO thickness and the VO/AZO interface roughness. The semiconductor-to-metal transition (SMT) properties of VO thin films are characterized and the transition temperature (T) is successfully tuned by the VO thickness as well as the VO/AZO interface roughness. It shows that the T of VO decreases with the decrease of film thickness or VO/AZO interface roughness. Other SMT properties of the VO films are maintained during the T tuning. The results suggest that the strain tuning induced by AZO buffer provides an effective approach for tuning T of VO continuously.

Light-weight aluminum (Al) alloys have widespread applications. However, most Al alloys have inherently low mechanical strength. Nanotwins can induce high strength and ductility in metallic materials. Yet, introducing high-density growth twins into Al remains difficult due to its ultrahigh stacking-fault energy. In this study, it is shown that incorporating merely several atomic percent of Fe solutes into Al enables the formation of nanotwinned (nt) columnar grains with high-density 9R phase in Al(Fe) solid solutions. The nt Al-Fe alloy coatings reach a maximum hardness of ≈5.5 GPa, one of the strongest binary Al alloys ever created. In situ uniaxial compressions show that the nt Al-Fe alloys populated with 9R phase have flow stress exceeding 1.5 GPa, comparable to high-strength steels. Molecular dynamics simulations reveal that high strength and hardening ability of Al-Fe alloys arise mainly from the high-density 9R phase and nanoscale grain sizes.

A simple one-step pulsed laser deposition (PLD) method has been applied to grow self-assembled metal-oxide nanocomposite thin films. The as-deposited Co-BaZrO films show high epitaxial quality with ultra-fine vertically aligned Co nanopillars (diameter <5 nm) embedded in a BZO matrix. The diameter of the nanopillars can be further tuned by varying the deposition frequency. The metal and oxide phases grow separately without inter-diffusion or mixing. Taking advantage of this unique structure, a high saturation magnetization of ∼1375 emu cm in the Co-BaZrO nanocomposites has been achieved and further confirmed by Lorentz microscopy imaging in TEM. Furthermore, the coercivity values of this nanocomposite thin films range from 600 Oe (20 Hz) to 1020 Oe (2 Hz), which makes the nanocomposite an ideal candidate for high-density perpendicular recording media.

Plasmonic oxide‐metal hybrid nanostructures exhibit unprecedented optical properties because of the nanoscale interactions between the oxide and metal components. Precise control of the geometry and arrangement of optical building blocks is key to tailoring system properties toward various nanophotonic applications. Herein, self‐assembled BaTiO3‐Au vertically aligned nanocomposite thin films with a series of thicknesses are fabricated using a one‐step pulsed laser deposition technique. By reducing the film thickness, the geometry of Au phase is effectively tailored from nanopillars to nanodisks, with the aspect ratio (height/width) varied from ≈4.0 to ≈1.0. The experimental optical spectra and numerical simulation results demonstrate that localized surface plasmon resonance and hyperbolic dispersion wavelength can be effectively tuned in the visible to near‐infrared regime by varying the film thickness due to the change of Au aspect ratio and free electron density. This study demonstrates a feasible approach in tuning the optical responses in hybrid oxide‐metal nanostructures, and opens up enormous possibilities in design and fabrication of novel optical components toward all optical integrated devices.