Thermo-spin effects in a quantum dot connected to ferromagnetic leads

TL;DR

This paper investigates thermospin effects in a quantum dot with ferromagnetic leads, revealing large spin thermopower and the ability to generate pure spin currents, with potential experimental applications.

Contribution

It introduces the concept of spin thermopower in quantum dot junctions and demonstrates tunability for pure spin current generation, a novel insight compared to bulk ferromagnets.

Findings

Spin thermopower can match the Seebeck coefficient in quantum dot junctions.

The junction can be tuned to produce only spin current without charge current.

Large spin figure of merit is achievable in the studied system.

Abstract

We study a system composed of a quantum dot in contact with ferromagnetic leads, held at different temperatures. Spin analogues to the thermopower and thermoelectric figures 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.