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Polycrystalline samples of Ru_1-xSb_xSr₂GdCuO₈ doped with Sb, in which magnetic order and superconductivity coexist with T_magnetic≫T_c, were prepared by a solid state reaction technique. Lattice parameters, electrical resistivity, Hall and thermopower coefficients measurements on the same sintered ceramic samples are presented.

Both Hall effect and thermopower show anomalous decreases below T_magnetic which might be explained with a simple two-band model in the RuO₂ layer at T_magnetic. It was also observed that the Sb doping reduce the conductivity of the system and the transition temperature decreases with increasing Sb content. This may be due to a distortion of RuO₆ octahedra which is responsible for the increase of hole localization.

The balance of forces on the superconducting condensate in the presence of currents is discussed. It is shown that the electrostatic potential known as the Bernoulli potential is a useful concept which allows one to establish conditions of a stationary motion.

In this study, the thermopower of pyrene molecule in both symmetric and asymmetric junctions to gold electrodes and the role of adding side group have been studied using density functional theory and Green’s function formalism in the linear response regime. We have considered four different configurations and investigated the thermopower property of them. Calculations show that adding electron donating side groups to both symmetrical and anti-symmetrical junction will increase the thermopower. However, the increase is more evident in asymmetric junction. Additionally, the Seebeck coefficient sign is positive which indicates p-type conduction.

A detailed study of charge transport properties of synthetic and genomic DNA sequences is reported. Genomic sequences of the Chromosome 22, λ-bacteriophage, and D1s80 genes of Human and Pygmy chimpanzee are considered in this work, and compared with both periodic and quasiperiodic (Fibonacci) sequences of nucleotides. Charge transfer efficiency is compared for all these different sequences, and large variations in charge transfer efficiency, stemming from sequence-dependent effects, are reported. In addition, basic characteristics of tunneling currents, including contact effects, are described. Finally, the thermoelectric power of nucleobases connected in between metallic contacts at different temperatures is presented.

We present a theoretical analysis of thermoelectric transport in the nonlinear regime. The thermopower and thermoconductance at finite temperature gradient are calculated numerically for a double barrier structure using Landauer Büttiker like formula. The thermopower is found to oscillate with the chemical potential. Thermopower can either be negative or positive which is well correlated with the behavior of the electric conductance. The thermal conductance is positive definite showing that the heat energy is always transferred from hot end to cold end. As the chemical potential is varied, nonlinear thermal conductance exists plateau-like features.

In the present work, the in-plane electron thermopower of semiconducting size-quantized films with nonparabolic energy band in a classically strong magnetic field, which is parallel to the film normal, are investigated. It was shown that, for the degenerate electron gas thermopower is a function of film thickness and electron density: for arbitrary thickness thermopower is oscillating function, with the period as a function of concentration, but with respect to concentration thermopower is monotonically increasing function. It is shown that in the case of ultrathin films (quantum wells) thermopower increases, as thickness decreases. This result is in agreement with the experimental dates on GaAs quantum wells.

Thermoelectric and thermomagnetic properties of graphene are analyzed using Boltzmann transport equation within the relaxation time approximation. Influence of temperature, charge carrier density and magnetic field on the thermopower and figure of merit is taken into account in the presence of different scattering processes. It is observed the magnetic field results in the increase of thermopower and figure of merit in the acoustical phonon scattering process, while they are reduced by charged impurity scattering.

The doping dependence of the thermopower of cuprate superconductors in the normal-state is studied within the $t$–$j$ model. It is shown that with a proper modification of the bare electron dispersion in the $t$–$j$ model, the experimental results of the doping dependence of the normal-state thermopower are qualitatively reproduced. In particular, the theory shows that a pseudogap-generated split of the van Hove peak in the density of states appears in the underdoped and optimally doped regimes, however, this split is absent from the overdoped regime. Concomitantly, the strong asymmetry of the spectral conductivity near the electron Fermi surface emerges, where the peak in the spectral conductivity appears always below the electron Fermi surface in the underdoped and optimally doped regimes, while it appears above the electron Fermi surface in the overdoped regime. This strong asymmetry of the spectral conductivity leads to the unusual behaviors of the normal-state thermopower from the underdoped regime to the overdoped regime.

Thermoelectric properties of a C₆₀ molecule coupled to three-dimensional metallic electrodes are studied using Green function formalism in linear response regime. A tight-binding model is used to investigate the effects of the dimerization and coupling geometry on the electrical conductance, thermopower and figure of merit. Increase of the contact points between the molecule and electrodes results in decrease of the number of the peaks of the electrical conductance because of the interference effects. In addition, oscillation of the thermopower is reduced in the multiple contacts. Results show that the increase of the contact points leads to the reduction of the figure of merit. Furthermore, the effect of the phase breaking scattering on the figure of merit is analyzed using the Büttiker probe method.

The doping and temperature dependent thermopower of SnTe is calculated from the first principles band structure using Boltzmann transport theory. We find that the p-type thermopower is inferior to PbTe consistent with experimental observations, but that the n-type thermopower is substantially more favorable.

We present numerical and analytical studies of the crossover between weak antilocalization and weak localization in monolayer graphene and their influence on thermopower. By the use of the recursive Green's function method, we find that these quantum corrections result in an enhancement of thermopower, which can be observed in the resulting magnetic field dependence. This magneto thermopower strongly depends on the size and strength of the impurities as well as on the back gate voltage of the system and the impurity concentration. We show in detail the crossover of these localization effects with these parameters. Using the disorder parameters of the numerical calculation, we find quantitative agreement with the analytical calculations.