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Thermoelectric effects in quantum dots with interaction

Sierra, Miguel A. (Supervisor: Sánchez, David)
Master Thesis , (2014)

Thermoelectric effects of small systems is a topic of great interest nowadays. We present an Anderson model for a quantum dot connected with two leads and we include Coulomb interactions with electrons with different spin in the dot. Afterwards, we calculate the current through the system using Green’s function formalism. We obtain two peaks in the conductance due to the Coulomb blockade effect. Then, we study the transport properties of this system in the voltage-driven case (no temperature differences) and in the temperature driven case (no voltage bias). In the first case, we find a smooth increasing function with the voltage difference which saturates at large voltage. Additionally, the conductance shows a diamond shape when it is depicted as a function of the voltage bias and the energy level of the dot. This is due to Coulomb interactions. In the temperature driven case, we find a strong nonlinear behaviour with a second zero of the thermocurrent when the Fermi level lies between the transmission peaks of the dot, finding that this behaviour is strongly related with Coulomb interactions. The thermovoltage also shows strongly nonlinear behaviour similarly to the thermocurrent. Finally, we also study the heat transport flux. We observe that there is an asymmetry when we change the sign of the voltage bias making the heat rectification parameter non zero for large voltage bias.