The superconducting fluctuation effect, due to droplets of preformed Cooper pairs above the critical temperature Tc, governs the temperature dependence of kinetic coefficients in superconductors at the onset of the phase transition. The transverse thermoelectric response - Nernst effect - is particularly sensitive to the fluctuations, and the large Nernst signal found in the various superconducting materials has raised much debate on its connection to the origin of unconventional superconductivity. In this thesis, we present a systematic study of the electrical and thermomagnetic transport phenomena in mesoscopic and paramagnetically (Pauli) limited superconductors.In the first chapter of this thesis we concentrate on the study of mesoscopic effects on transport in superconductors. We find that long-range phase coherence developing close to Tc triggers a great amplification of mesoscopic fluctuations due to strong pairing correlations. As a result, mesoscopic conductance fluctuations cease to be universal and exhibit pronounced dependence on temperature. Despite the lack of universality, in the sense of random matrix theory classification, we have discovered a different kind of universality in terms of temperature dependence of fluctuating characteristics. We find that mesoscopic fluctuations of conductivity, transversal thermoelectric coefficient and diamagnetic susceptibility consistently display the same scaling with temperature close to Tc. We connect our results to the existing experimental measurements of conductance fluctuations in superconducting films. Experimental verification of the temperature scaling and the overall magnitude ofthe mesoscopic fluctuations of Nernst coefficient will provide a powerful tool for a better understanding of thermomagnetic transport phenomena in correlated systems.In the second chapter of this thesis we examine the electrical and thermal transport anomalies in the ultra-thin superconducting films in an external in-plane magnetic field. We concentrate on the Clogston-Chandrasekhar phase transition, i.e., the destruction of superconductivity by a magnetic field by virtue of the Zeeman splitting. Near the quantum critical point of the supercooling line in the phase diagram, we discover highly non-monotonic magnetoresistance. The most remarkable feature of this effect is that fluctuation-induced transport is dominated by the virtual excitations rather than real preformed Cooper pairs. We also carefully study how spin-orbit scattering and other pair-breaking effects modify the fluctuation transport. In the strong spin-orbit scattering regime, we find that the scaling of the thermomagnetic coefficient is the same as conductivity within the classical region of transition, however they are drastically different near the quantum critical point. Even though we primarily focus on the conventional superconductors our result for the Nernst effect may have important implications to the other systems, such as iron-pnictides, and in particular to FeSe compound, which has comparable Zeeman and superconducting gaps.
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