Spin-dependent thermoelectric effects in graphene based superconductor junctions

TL;DR

This paper explores how spin-dependent thermoelectric effects in graphene-based superconductor junctions can be controlled by Rashba spin-orbit interaction, revealing potential for spin-caloritronics applications.

Contribution

It demonstrates the significant impact of Rashba spin-orbit interaction on charge and spin thermoelectric effects in graphene superconductor junctions, a novel insight.

Findings

Spin thermopower is temperature-dependent in graphene-based junctions.

Maximum Seebeck coefficients reach up to 3.5$k_B/e$ for charge and 2.5$k_B/e$ for spin.

Rashba interaction is essential for observed thermoelectric effects.

Abstract

Using the Bogoliubov de-Gennes formalism, we investigate the charge and spin-dependent thermoelectric effects in superconductor graphene junctions. Results demonstrate that despite normal-superconductor junctions, there is a temperature-dependent spin thermopower both in the graphene-based ferromagnetic-superconductor (F-S) and ferromagnetic-Rashba spin-orbit region-superconductor (F-RSO-S) junctions. It is also shown that in the presence of Rashba spin-orbit interaction, the charge and spin-dependent Seebeck coefficients can reach to their maximum up to 3.5$k_B/e$ and 2.5$k_B/e$, respectively. Remarkably, these coefficients have a zero-point critical value with respect to magnetic exchange field and chemical potential. This effect disappears when the Rashba coupling is absent. These results suggest that graphene-based superconductors can be used in spin-caloritronics devices.