Phase-modulated thermoelectric transport in a four-terminal ferromagnet/superconductor junction

Abstract

We theoretically investigate the spuerconducting phase-modulated thermoelectric transport in a four-terminal ferromagnet/superconductor junction driven by a thermal gradient, in which a central quantum dot (QD) is coupled to two superconductors and two ferromagnetic leads. Both the Cooper pair splitting (CPS) and the elastic cotunneling (EC) can contribute to electric and heat currents. When the thermally induced electric current only originates from the CPS (EC), it is an even (odd) function of the QD level. The relative contributions of the CPS and EC can be modulated by the Zeeman field in the QD and the superconducting phase difference. Intriguingly, a Zeeman field controlled heat switch effect has been demonstrated. Furthermore, by varying the Zeeman field direction the heat current exhibits a conversion from a dip to a peak. These features can help us to distinguish the CPS from the EC and to design phase-coherent caloritronics devices.