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[en] In this note we consider the geometrical effects of a percolating system on the nonlinear transport properties in a superconductor-normal conductor nonlinear resistor network. For realistic composites, the nonlinearity may play an important role in the electrical transport phenomena. A typical example consists of studying a nonlinear composite medium in which an inclusion with nonlinear current-field (J-E) characteristics is randomly embedded in a host with either linear or nonlinear J-E response. For such a system, substantial progress in studies of the effective nonlinear response has been made in the past few years
[en] A high-resolution scanning superconducting quantum interference device microscopy study of tetragonal single-layer Ti2Ba2CuO6+δ films, deposited on tricrystal SrTiO3 substrates, demonstrates the effect of spontaneously generated half flux quanta. This observation shows that in addition to YBa2Cu3O7, the order parameter symmetry in TI2Ba2CuO6+δ is consistent with that of a dx2-y2 pair state. This result also rules out any bilayer or twinning effects and any pairing that is incompatible with the fourfold rotational symmetry as in the Ti2Ba2CuO6+δ superconducting system. 18 refs., 5 figs
[en] Electrical resistivity, thermoelectric power and Hall coefficient have been measured for an antiferromagnetic heavy fermion compound Ce7Ni3. Above 30 K the magnetic resistivity ρm has a logarithmic temperature dependence -ln T and the large value of ρ below the Neel temperature TN=1.8 K indicates that the magnetic state below TN is gap-type antiferromagnetic. For the thermoelectric power, the large negative peak due to magnetic contribution appears at 5 K, vanishes by slight substitution of La for Ce, and the positive peak due to Kondo contribution appears. The temperature dependence of the Hall coefficient RH above and below 30 K is explained with the skew scattering model and with the anomalous velocity model, respectively. (orig.)
[en] It is shown that the fractal dimension of Sierpinski gasket as a conductor is different from that for its geometry. The fractal dimension of Sierpinski gasket can be defined as D = DΕ + iDR. DΕ and DR are the fractal dimensions determined from its conductance and resistance, respectively. For 2-d Sierpinski gasket DR = 3.8 and DΕ = 1/DR = 0.263, while for 3-d Sierpinski tetrahedron DR = 2.41 and DΕ = 0.415. (author). 4 refs, 5 figs
[en] The effective properties of composites whose structure includes nanocontacts between bulk-phase macrocrystallites are considered. A model for such a nanostructured composite is constructed. Effective values of the thermoelectric power, thermal and electrical conductivities, and thermoelectric figure of merit are calculated in the mean-field approximation.
[en] A new resistive mode is shown to exist in rotating plasma columns. The mode is localized in the neighbourhood of the radius where the angular velocity of the bulk plasma is equal to minus half the local angular velocity of the ions. This singular point is caused by the Hall term in the generalized Ohm law. The growth rate of the mode scales with eta sup(1/2), where eta is the plasma resistivity. (Author)
[pt]E demonstrado que um novo modo resistivo e instavel em colunas de plasma com rotacao. O modo e localizado na vizinhanca do raio onde a velocidade angular do plasma e igual a metade da velocidade angular local dos ions e em sentido contrario. Este ponto singular e causado pelo termo de Hall na lei de Ohm generalizada. A razao de crescimento do modo e proporcional a eta sup(1/2), onde eta e a resistividade do plasma. (Autor)
[en] The electrical conductivity and volt-ampere characteristics of the p-CuTlS single crystal with specific resistance ρ= 40 Ω·cm and irradiated by γ-quantum were studied in the range of 100-300 K temperature and 10-104 V/cm. It was determined that the cause of the conduction disorder observed in the CuTlS single crystal at low electric fields and high radiation doses is the formation of defect clusters dominated by cation vacancies. A sharp increase in current at high electric fields and temperatures occurs as a result of thermo-field ionization of the acceptor level with activation energy ΔEa=0,08 eV and the ionization voltage decreases with increasing radiation dose. Based on the determination of the parameters (λ, rm, n0, ε) that determine the mechanism of current flow, the dependence of the shape of the potential hole on the radiation dose was determined.