Pangpang Wang

Effect of an interface charge density wave on surface plasmon resonance in ZnO/Ag/ZnO thin films

The optical transmission spectra of ZnO/Ag/ZnO films showed a broad range of transmission enhancement due to a harmonic generated by surface plasmon resonance. This resonance was correlated with interface electrons between metallic Ag and dielectric ZnO layer. The interface charge density wave was calculated and compared with experimental results using Maxwell’sequations with a modified boundary condition. Finally, an observed redshift in the transmission enhancement is discussed using both the Ohmic contact model and the Drude free electron model.

Enhancement of light transmission by coupling to surface plasmon polaritons of a layer-plus-islands silver layer

Enhanced light transmission through coupling incident light with surface plasmon polaritons (SPPs) on a layer-plus-islands nanostructure Ag layer, surrounded by symmetric ZnO dielectrics (ZnO/Ag/ZnO), was investigated. The couple and decouple processes at ZnO/Ag and Ag/ZnO grating interfaces were considered to confine the incident light to SPPs (near field) and then to excite the SPPs to radiate light (far field), which enhanced light transmission. A broad range of light transmission enhancement showed a blueshift with increasing Ag midlayer mass thickness. The physical reasons for light transmission enhancement were theoretically discussed using both the metal/dielectric grating interface model and the Drude–Lorentz free electron model.

Effect of silver evolution on conductivity and transmittance of ZnO/Ag thin films

ZnOfilms with an embedded silver layer, one of the most promising transparent conductive materials, possess excellent conductivity and optical transmittance. The performance of ZnOfilms is greatly affected by the morphology of the silver layer. In this work, we studied the changes in the electrical and optical properties of ZnO/Ag multilayered films as a function of the coalescence of the silver clusters. Silver clusters aggregated into various morphologies at different layer growth stages and dominantly affected the conductivity of ZnO/Ag films as a result of different electron transport mechanisms. The optical transmittance was also enhanced by surface plasmon resonance between the incident light and the random grating of the silver clusters. The improved electrical conductivity and optical transmittance give asymmetric ZnO/Ag multilayered films the potential to be used as transparent electrodes.

A multistep ac electrodeposition method to prepare Co nanowires with high coercivity

It is known that the ac electrodeposition method with low current density can grow compact metal nanowires, but the length of those nanowires is very short. In contrast, the ac electrodeposition method with high current density can grow long metal nanowires. However these long nanowires are not compact and contain lots of defects. In this paper, we describe a multistep ac electrodeposition method to fabricate long metal nanowires with compact structure uniformly filled upon a porous anodic aluminum oxide template. Using this method, Co nanowires with high coercivity (Hc∥) and remnant ratio (Mr/Ms) have been prepared under relatively low deposition current density. The Co nanowires exhibited obvious magnetic anisotropy with the easy axis along the axial direction of nanowires. The maximal Hc∥ (2900 Oe) and Mr/Ms (0.95) were optimal for the perpendicular magnetic recording materials. The magnetic microstructure of Co nanowires is also discussed in this paper.

Photoluminescence modulation of ZnO via coupling with the surface plasmon resonance of gold nanoparticles

In this letter, we study how coupling between AuNPs and ZnO thin films affects their emission properties. The emission intensity of ZnO thin films changes when Al2O3 spacer layer of different thickness is included in ZnO/Au films, consistent with theoretical predictions. The emission properties are also controlled using the polarization of the excitation source. Emission properties depended on the polarization of the excitation source because of the surface plasmon resonance of AuNPs. The photoluminescence anisotropy of these systems shows that enhanced photoluminescence can be achieved through coupling of the emission from ZnO with the surface plasmon resonance of AuNPs.

MAGNETIC PROPERTIES OF FENI NANOWIRE ARRAYS ASSEMBLED ON POROUS AAO TEMPLATE BY AC ELECTRODEPOSITION

FeNi nanowire arrays were fabricated into the pores of porous alumina template by a simple alternating current electrodeposition method in this work. FeNi nanowires with different diameters were obtained depending on the pore size arrangement of alumina templates. FeNi nanowire arrays exhibited obviously magnetic anisotropy, and the easy axis was along the nanowires. When the applied magnetic field was parallel to the nanowires, the coercivity (Hc) and the maximum remnant ratio (Mr/Ms) are considerable higher than those while the magnetic field perpendicular to the nanowires. FeNi nanowires prepared in this work are expected to be utilized as the perpendicular magnetic recording media. The magnetic domain structure and the magnetizing mechanism of FeNi nanowires were also been discussed.

Structure transition and magnetism of bcc-Ni nanowires

Body-centered-cubic (bcc) Ni nanowires were successfully synthesized by multistep ac electro-deposition on anodic aluminum oxide templates. bcc-Ni is ferromagnetic with a lattice constant of 0.288 nm, and bcc-Ni to fcc-Ni phase transition occurs under heat treatment. Magnetic measurements suggest that the ferromagnetic transition of bcc-Ni nanowires involves a structure change evolving from bcc to fcc in the magnetic-ordering process. Furthermore, the processes of structure transition in bcc-Ni nanowires under the heating conditions were observed in situ using transmission electron microscopy. In addition, our work also establishes that fcc-Ni nanowires and bulk Ni have only a ferromagnetic transition at the Curie point, involving no crystal structure change.