Superconducting Fluctuation Corrections to the Thermal Current in Granular Metals

The first-order superconducting fluctuation corrections to the thermal conductivity of a granular metal are calculated. A suppression of thermal conductivity proportional to $T_c/(T-T_c)$ is observed in a region not too close to the critical temperature $T_c$. As $T\simeq T_c$, a saturation of the correction is found, and its sign depends on the ratio between the barrier transparency and the critical temperature. In both regimes, the Wiedemann-Franz law is violated.Comment: 9 pages, 7 figures. Replaced with published version. Important change

Weak localization effects in granular metals

The weak localization correction to the conductivity of a granular metal is calculated using the diagrammatic technique in the reciprocal grain lattice representation. The properties of this correction are very similar to that one in disordered metal, with the replacement of the electron mean free path $\ell$ by the grain diameter $d$ and the dimensionless conductance $g$ by the tunnelling dimensionless conductance $g_{T}$. In particular, we demonstrate that at zero temperature no conducting phase can exist for dimensions $D\leq 2$. We also analyze the WL correction to magnetoconductivity in the weak field limit.Comment: 4 pages, 3 figures; minor corrections adde

Organic dye for dye-sensitized solar cell

Organic dye for a dye-sensitized solar cell (DSSC) comprising at least one electron-acceptor unit and at least one π-conjugated unit. Said organic dye is particularly useful in a dye-sensitized photoelectric transformation element which, in its turn, can be used in a dye-sensitized solar cell (DSSC)

Organic dye for dye-sensitized solar cells

Organic dye for a dye-sensitized solar cell (DSSC) comprising at least one electron-acceptor unit and at least one π-conjugated unit. Said organic dye is particularly useful in a dye-sensitized photoelectric transformation element which, in its turn, can be used in a dye-sensitized solar cell (DSSC)

Organic dye for dye-sensitized solar cells

Organic dye for a dye-sensitized solar cell (DSSC) comprising at least one electron-acceptor unit and at least one π-conjugated unit. Said organic dye is particularly useful in a dye-sensitized photoelectric transformation element which, in its turn, can be used in a dye-sensitized solar cell (DSSC)

Magnetic-field-induced Luttinger liquid

It is shown that a strong magnetic field applied to a bulk metal induces a Luttinger-liquid phase. This phase is characterized by the zero-bias anomaly in tunneling: the tunneling conductance scales as a power-law of voltage or temperature. The tunneling exponent increases with the magnetic field as BlnB. The zero-bias anomaly is most pronounced for tunneling with the field applied perpendicular to the plane of the tunneling junction.Comment: a reference added, minor typos correcte

Reentrant Metallic Behavior of Graphite in the Quantum Limit

Magnetotransport measurements performed on several well-characterized highly oriented pyrolitic graphite and single crystalline Kish graphite samples reveal a reentrant metallic behavior in the basal-plane resistance at high magnetic fields, when only the lowest Landau levels are occupied. The results suggest that the quantum Hall effect and Landau-level-quantization-induced superconducting correlations are relevant to understand the metallic-like state(s) in graphite in the quantum limit.Comment: 4 pages, 5 figure

Lepton pairs from thermal mesons

We study the net dielectron production rates from an ensemble of thermal mesons, using an effective Lagrangian to model their interaction. The coupling between the electromagnetic and the hadronic sectors is done through the vector meson dominance approach. For the first time, a complete set of light mesons is considered. We include contributions from decays of the type V~(PS)~$\rightarrow$~PS~(V)~+~$e^+~e^-$, where V is a vector meson and PS is a pseudoscalar, as well as those from binary reactions PS~+~PS, V~+~V, and V~+~PS~$\rightarrow~e^+e^-$. Direct decays of the type V~$\rightarrow~e^+ e^-$ are included and shown to be important. We find that the dielectron invariant mass spectrum naturally divides in distinct regions: in the low mass domain the decays from vector and pseudoscalar mesons form the dominant contribution. The pion--pion annihilation and direct decays then pick up and form the leading signal in an invariant mass region that includes the $\rho - \omega$ complex and extends up to the $\phi$. Above invariant mass $M\ \approx$~1~GeV other two-body reactions take over as the prominent mechanisms for lepton pair generation. These facts will have quantitative bearing on the eventual identification of the quark--gluon plasma.Comment: In ReVTeX 3.0, 9 figs. available from above email address. McGill 93/8, TPI-MINN-93/19-