Non-equilibrium thermoelectric transport through a hybrid nano-junction
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2018
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Abstract
This thesis is focused in the study of transport phenomena in strongly correlated systems. Particularly we have evaluated the non-equilibrium thermoelectric transport current and thermoelectric transport coefficients of a hybrid system, composed by a quantum dot connected to a normal s-wave superconductor and a topological superconductor leads, using the Keldysh formalism and Floquet theory. Due the non-conventional terminals, these system presents interesting correlations between different kind of quasi-particles, in particular, Cooper pairs and Majorana Fermions. The later are characterized by a non-abelian statistics and its discover in strongly correlated systems has opened new research horizons for the condensed matter community. Our results show a non-linear electrical current for different magnetic fields, whose peaks are signatures of Majorana Bound States. We also show that the transport processes are highly mediated by Andreev reflections and Andreev bound states, which are the principal mechanism present in the superconducting proximity effect of these kind of systems. Starting from the electrical current, we have evaluated the thermoelectric performance of the system for different magnetic fields, characterized by the Seebeck coefficient S, electrical and thermal conductivities σ, κ, Lorenz number L and the figure of merit ZT,which reaches its maximum value ZT = 0.02∆/kB at a finite magnetic field H = 0.3∆ at an applied bias voltage 0.7eV/∆. We also found that this system has a Lorenz number which achieves a maximum and minimum values far apart to those reported for Fermi liquids, violating the Wiedemann-Franz law.
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Tesis (Master in Physics)--Pontificia Universidad Católica de Chile, 2018