Transparent and electrically conductive composite silica films were fabricated on glass and hydrophilic SiOx/silicon substrates by incorporation of individual graphene oxide sheets into silica sols followed by spin-coating, chemical reduction, and thermal curing. The resulting films were characterized by SEM, AFM, TEM, low-angle X-ray reflectivity, XPS, UV-vis spectroscopy, and electrical conductivity measurements. The electrical conductivity of the films compared favorably to those of composite thin films of carbon nanotubes in silica.

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Recent years have witnessed a rapidly growing interest in exploring the use of spin waves for information transmission and computation toward establishing a spin-wave-based technology that is not only significantly more energy efficient than the CMOS technology, but may also cause a major departure from the von-Neumann architecture by enabling memory-in-logic and logic-in-memory architectures. A major bottleneck of advancing this technology is the excitation of spin waves with short wavelengths, which is a must because the wavelength dictates device scalability. Here, we report the discovery of an approach for the excitation of nm-wavelength spin waves. The demonstration uses ferromagnetic nanowires grown on a 20-nm-thick Y3Fe5O12 film strip. The propagation of spin waves with a wavelength down to 50 nm over a distance of 60,000 nm is measured. The measurements yield a spin-wave group velocity as high as 2600 m s−1, which is faster than both domain wall and skyrmion motions.

The annealing effects on structure and magnetism for Co-doped ZnO films under air, Ar, and Ar/ H 2 atmospheres at 250°C have been systematically investigated. Room-temperature ferromagnetism has been observed for the as-deposited and annealed films. However, the saturation magnetization ͑M s ͒ varied drastically for different annealing processes with M s ϳ 0.5, 0.2, 0.9, and 1.5 B / Co for the as-deposited, air-annealed, Ar-annealed, and Ar/ H 2-annealed films, respectively. The x-ray absorption spectra indicate all these samples show good diluted magnetic semiconductor structures. By comparison of the x-ray near edge spectra with the simulation on Zn K edge, an additional preedge peak appears due likely to the formation of oxygen vacancies. The results show that enhancement ͑suppression͒ of ferromagnetism is strongly correlated with the increase ͑decrease͒ of oxygen vacancies in ZnO. The upper limit of the oxygen vacancy density of the Ar/ H 2-annealed film can be estimated by simulation to be about 1 ϫ 10 21 cm −3 .

We observe strong interlayer magnon-magnon coupling in an on-chip nanomagnonic device at room temperature. Ferromagnetic nanowire arrays are integrated on a 20-nm-thick yttrium iron garnet (YIG) thin film strip. Large anticrossing gaps up to 1.58 GHz are observed between the ferromagnetic resonance of the nanowires and the in-plane standing spin waves of the YIG film. Control experiments and simulations reveal that both the interlayer exchange coupling and the dynamical dipolar coupling contribute to the observed anticrossings. The coupling strength is tunable by the magnetic configuration, allowing the coherent control of magnonic devices.

Magnon spintronics is a prosperous field that promises beyond-CMOS technology based on elementary excitations of the magnetic order that act as information carriers for future computational architectures. Unidirectional propagation of spin waves is key to the realization of magnonic logic devices. However, previous efforts to enhance the Damon-Eshbach-type nonreciprocity did not realize (let alone control) purely unidirectional propagation. Here we experimentally demonstrate excitations of unidirectional exchange spin waves by a nanoscale magnetic grating consisting of Co nanowires fabricated on an ultrathin yttrium iron garnet film. We explain and model the nearly perfect unidirectional excitation by the chirality of the magneto-dipolar interactions between the Kittel mode of the nanowires and the exchange spin waves of the film. Reversal of the magnetic configurations of film and nanowire array from parallel to antiparallel changes the direction of the excited spin waves. Our results raise the prospect of a chiral magnonic logic without the need for fragile surface states.Spin waves (SWs) 1-6 can transport information in high-quality magnetic insulators such as yttrium iron garnet (YIG) 7-10 free of charge flow and with very low dissipation. Based on the interference and nonlinear interactions, the phase information of SWs 11-14 allows the design of wave-based logic circuits 15-17 for information transmission and processing with small environmental footprint. Surface SWs 18 are chiral, i.e. they propagate only in the direction of the outer product of magnetization direction and surface normal and, therefore, in opposite directions on the upper and lower film surfaces/interfaces. These "Damon-Eshbach" (DE) modes 18 are beneficial for magnonic logic devices 19 but exist only in thick magnetic films with sizable group velocities. As products of the dipolar magnetic interaction, in the case of thin films, they have small group velocities and are susceptible to surface roughness scattering. Previous efforts focused on magnetic metallic systems 20-28 with relative high dissipation. Short-wavelength spin waves 29-36 with dispersion governed by the exchange interactions, travel much faster at higher frequencies (Fig. 1d). However, pure exchange

In purely bent ZnO microwires, the excitons can be effectively driven and concentrated by the elastic strain-gradient towards the tensile outer side of the purely bent wire. Experimental and theoretical approaches are combined to investigate the dynamics of excitons in an inhomogeneous strain field with a uniform elastic strain-gradient. Cathodoluminescence spectroscopy analysis on purely bent ZnO microwires verifies that excitons can be effectively driven and concentrated along the elastic strain-gradient.

A multi-source/component spray coating process to fabricate the photoactive layers in polymer solar cells is demonstrated. Well-defined domains consisting of polymer:fullerene heterojunctions are constructed in ambient conditions using an alternating spray deposition method. This approach preserves the integrity of the layer morphology while forming an interpenetrating donor (D)/acceptor (A) network to facilitate charge transport. The formation of multi-component films without the prerequisite of a common solvent overcomes the limitations in conventional solution processes for polymer solar cells and enables us to process a wide spectrum of materials. Polymer solar cells based on poly(3-hexylthiophene):[6,6]-phenyl C(61) butyric acid methyl ester spray-coated using this alternating deposition method deliver a power conversion efficiency of 2.8%, which is comparable to their blend solution counterparts. More importantly, this approach offers the versatility to independently select the optimal solvents for the donor and acceptor materials that will deliver well-ordered nanodomains. This method also allows the direct stacking of multiple photoactive polymers with controllable absorption in a tandem structure even without an interconnecting junction layer. The introduction of multiple photoactive materials through multisource/component spray coating offers structural flexibility and tenability of the photoresponse for future polymer solar cell applications.