Enhanced thermoelectric properties of graphene-based ferromagnetic-superconductor junctions, Andreev reflection effect

We have theoretically studied ballistic graphene-based Ferromagnetic/Superconductor (FG/SG) junction operated as thermoelectric generators. Ferromagnetism and superconductivity in graphene are assumed to be induced by superconducting and ferromagnetic electrodes placed on the top of the graphene sheet. We calculate the normal and Andreev reflection probabilities using the Blonder-Tinkham-Klapwijk (BTK) formalism to solve a four-dimensional version of the Dirac-Bogoliubov-de Gennes equation. By a special choice of system parameters it is possible to achieve a condition in which thermal conductance declines significantly while electrical conductance increases. We also calculate output power and thermoelectric power-conversion efficiency at low temperature based on such a structure and show that the power generation efficiency is close to the Carnot limit.