Quantum point contact conductance in normal metal/insulator/ metal/dx2−y2+idxy mixed wave superconductor junctions

The tunneling conductance in a normal metal/insulator/metal/$d_{x^2?y^2}+i{d}_{xy}$ mixed wave superconductor (N/I/N/$d_{x^2?y^2}+i{d}_{xy}$) junction is calculated, where the N/I/N region is a quantum wire. It is found in the single-mode case that the magnitude of the tunneling conductance near zero voltage is enhanced due to the Andreev bound state by quasiparticles with perpendicular and horizontal injection, and the zero-bias conductance varies with $L$ ($L$ is the distance from insulating layer to the interface of N/$d_{x^2?y^2}+i{d}_{xy}$ mixed wave superconductor). Splitting of the zero-bias conductance peak appears in the quantum point contact tunneling spectra for an N/I/N/$d_{x^2?y^2}+i{d}_{xy}$ junction, and several subgap peaks can split at the same time. On increasing both $L$ and the magnitude ratio of the two components for the $d_{x^2?y^2}+i{d}_{xy}$ mixed wave, the subgap resonances exhibit an alternately high and low behavior inside the energy gap. These results are different from those in d-wave and p-wave superconductor junctions.     

Spin-glass behavior in the antiperovskite manganese nitride Mn3CuN codoped with Ge and Si

Antiperovskite manganese nitrides ${\mathrm{Mn}}_3\left({\mathrm{Cu}}_{0.6}{\mathrm{Si}}_x{\mathrm{Ge}}_{0.4?x}\right)N$ ($x=0.05$, 0.1, 0.15) were prepared and their negative thermal expansion, magnetic and specific heat properties were investigated. A frozen state with a freezing temperature was found at ～207 K in ${\mathrm{Mn}}_3\left({\mathrm{Cu}}_{0.6}{\mathrm{Si}}_{0.15}{\mathrm{Ge}}_{0.25}\right)N$. This indicates that ${\mathrm{Mn}}_3\left({\mathrm{Cu}}_{0.6}{\mathrm{Si}}_{0.15}{\mathrm{Ge}}_{0.25}\right)N$ exhibits a spin glass state at low temperatures. We discussed the cause of spin glass behavior and correlated this spin glass behavior with broadening of the negative thermal expansion operation-temperature window of the manganese nitrides ${\mathrm{Mn}}_3\left({\mathrm{Cu}}_{0.6}{\mathrm{Si}}_{0.15}{\mathrm{Ge}}_{0.25}\right)N$.     

Effect upon universal order of Hubble expansion

The level of order $R$ in a spherical system of radius $r_0$ with a probability amplitude function $\psi \left(x\right),x=r,\theta ,?$ obeys $R=(1/2)r_0^{2}I$, where $I=4\int dx{\left|?\psi \right|}^2$ is its Fisher information level. We show that a flat space universe obeying the Robertson–Walker metric has an invariant value of the order as it undergoes either uniform Hubble expansion or contraction. This means that Hubble expansion per se does not cause a loss of universal order as time progresses. Instead, coarse graining processes characterizing decoherence and friction might cause a loss of order. Alternatively, looking backward in time, i.e. under Hubble contraction, as the big bang is approached and the Hubble radius $r_0$ approaches small values, the structure in the amplitude function $\psi \left(x\right)$ becomes ever more densely packed, increasing all local slopes $?\psi$ and causing the Fisher information $I$ to approach unboundedly large values. As a speculation, this ever-well locates the initial position of the universe in a larger, multiverse.     

Electric field and temperature dependence of hole mobility in electroluminescent PDY 132 polymer thin films

The current density–voltage ($J\text{–}V$) behavior of polymer PDY 132 thin films has been investigated in hole-only device configuration, viz., ITO/poly(ethylene-dioxthiophene):polystyrenesulphonate (PEDOT:PSS)/PDY 132/Au, as a function of polymer (PDY) film thickness (150 nm and 200 nm) and temperature (290–90 K). Hole current density was found to follow two distinct modes of conduction, (i) low electric field region I: ohmic conduction where slope $～1$, and (ii) intermediate and high electric field region II: non ohmic conduction where slope $～2$. Region I has been attributed to the transport of intrinsic background charge carriers while region II has been found to be governed by space charge limited currents (SCLC) with hole mobility strongly dependent on electric field and temperature. The respective hole transport parameters determined from the SCLC regime, ${\mu }_{p0}$ is $3.7\times 10^{?3}{m}^2/Vs$, ${\mu }_p(0,T)$ is $3.7\times 10^{?8}{m}^2/Vs$, and zero field activation energy (${\Delta }_0$) of 0.48 eV is obtained.     

Photoluminescence of ZnO ceramics sintered with a flux

ZnO ceramics both with and without boric acid as a flux were sintered at $T_S=800\text{–}1200{}^{°}C$ and their luminescent characteristics were compared. In obtained samples UV as well as visible emission bands were observed. The addition of the flux was shown to cause the increase of grain size and the improvement of crystalline quality of the ceramics, which was ascribed to the creation of a liquid phase during the sintering process. It was found that the adding of 1 wt% of boric acid to ZnO powder allowed ceramics preparation without any pressing of the starting materials, in this case $T_S=950{}^{°}C$ being enough to obtain firm and dense ceramics. This ceramics had higher intensity of UV emission and lower intensity of visible emission than ceramics sintered without the flux.     

Invariant surfaces of a three-dimensional manifold with constant Gauss curvature

We give a reduction procedure to determine (locally) the surfaces with constant Gauss curvature in a three-dimensional manifold which are invariant under the action of a one-parameter subgroup of the isometry group of the ambient space. We apply this procedure to describe the invariant surfaces with constant Gauss curvature in $H^2\times R$ and in $H_3$.