Thermospin effects in a quantum dot connected to ferromagnetic leads

TLDR

The study investigates a quantum dot coupled to ferromagnetic leads at different temperatures, defining and analyzing spin analogs of thermopower and the thermoelectric figure of merit as functions of junction parameters. The authors model the quantum dot–lead junction, compute spin thermopower and figure of merit, and discuss experimental setups to test the predictions. The spin‑thermopower coefficient can reach the magnitude of the Seebeck coefficient, yielding a large spin figure of merit, and the junction can be tuned to deliver pure spin current without charge current.

Abstract

We study a system composed of a quantum dot in contact with ferromagnetic leads held at different temperatures. Spin analogs to the thermopower and thermoelectric figure of merit are defined and studied as a function of junction parameters. It is shown that in contrast to bulk ferromagnets, the spin-thermopower coefficient in a junction can be as large as the Seebeck coefficient, resulting in a large spin figure of merit. In addition, it is demonstrated that the junction can be tuned to supply only spin current but no charge current. We also discuss experimental systems where our predictions can be verified.