First-principles calculations are employed to investigate the phonon transport of BiCuOSe. Our calculations reproduce the lattice thermal conductivity of BiCuOSe. The calculated grüneisen parameter is 2.4 ~ 2.6 at room temperature, a fairly large value indicating a strong anharmonicity in BiCuOSe, which leads to its ultralow lattice thermal conductivity. The contribution to total thermal conduc...

We report the complex optical conductivity of a superconducting thin film of Nb 0.5 Ti 0.5 N in an external magnetic field. The field was applied parallel to the film surface and the conductivity extracted from far-infrared transmission and reflection measurements. The real part shows the superconducting gap, which we observe to be suppressed by the applied magnetic field. We compare our result...

The interplay of electron-electron interactions and spin-orbit coupling leads to a new contribution to the homogeneous optical conductivity of the electron liquid. The latter is known to be insensitive to many-body effects for a conventional electron system with parabolic dispersion. The parabolic spectrum has its origin in the Galilean invariance which is broken by spin-orbit coupling. This op...

We study the effect of electron-electron interactions in the optical conductivity of graphene under an applied gate and derive a generalization of Elliott's formula, commonly used for semiconductors, for the optical intensity. We show that excitonic resonances are responsible for several features of the experimentally measured midinfrared response of graphene such as the increase of the conduct...

ZnO and ZnO: Mn nanocrystals synthesized via reverse micelle method. The structural properties nanocrystals were investigated by XRD and Transmission electron microscopy (TEM). The XRD results indicate that the synthesized nanocrystals had a pure wurtzite (hexagonal phase) structure. The various optical properties of these nanocrystals such as optical band gap energy, refractive index, dielectr...

nanofber  mats  of  poly(ε-caprolactone)/nanoclay  nanocomposites  were fabricated by electrospinning. the effects of the solution concentration and  the  nanoclay  content  of  nanocomposite  materials  on  the  fnal nanofber  structure were  investigated. morphology  and  diameter  of  the  nanofbers were studied using optical and scanning electron microscope. it was observed that the  poly(ε...

–Expressions are obtained for the thermal conductivity of some ABO3 type displacive ferroelectrics in paraelectric phase, using Kubo formalism and double time thermal Green’s function technique. The total thermal conductivity obtained for these perovskites which is sum of two terms contributed by optical and acoustical phonons, is in agreement with the experimental results of Steigmeier. The va...

The optical conductivity spectra of quasi-one dimensional compounds K0.3Mo1−xWxO3 (x=0, 0.03 and 0.15) have been studied over broad frequencies. While the dc resistivity measurements indicate no sign of CDW transition in heavily W-doped blue bronze, the optical conductivity spectra still show a single particle gap at around 0.2 eV for E parallel to the chain direction. Such impurity effect chal...

zno and zno: mn nanocrystals synthesized via reverse micelle method. the structural properties nanocrystals were investigated by xrd and transmission electron microscopy (tem). the xrd results indicate that the synthesized nanocrystals had a pure wurtzite (hexagonal phase) structure. the various optical properties of these nanocrystals such as optical band gap energy, refractive index, dielectr...

We report an investigation on the optical properties of Cu3Ge thin films displaying very high conductivity, with thickness ranging from 200 to 2000 Å, deposited on Ge substrates. Reflectance, transmittance, and ellipsometric spectroscopy measurements were performed at room temperature in the 0.01–6.0, 0.01–0.6, and 1.4–5.0 eV energy range, respectively. The complex dielectric function, the opti...