Thermal Transport Properties of Graphene-Based F/S/F Junctions

TL;DR

This paper studies heat transport in graphene-based F/S/F junctions, revealing oscillatory thermal conductance due to Dirac fermion interference, and identifies conditions for minimal conductance related to exchange field and superconducting width.

Contribution

It introduces the first detailed analysis of thermal conductance oscillations in graphene F/S/F junctions caused by Dirac fermion interference effects.

Findings

Thermal conductance oscillates with superconducting region width.

Minimal conductance occurs at exchange field h/E_F ≈ 1.

Thermal conductance increases linearly with temperature for thin superconducting regions.

Abstract

We present an investigation of heat transport in gapless graphene-based Ferromagnetic /singlet Superconductor/Ferromagnetic (FG$\mid$SG$\mid$FG) junctions. We find that unlike uniform increase of thermal conductance vs temperature, the thermal conductance exhibits intensive oscillatory behavior vs width of the sandwiched s-wave superconducting region between the two ferromagnetic layers. This oscillatory form is occurred by interference of the massless Dirac fermions in graphene. Also we find that the thermal conductance vs exchange field $h$ displays a minimal value at $h/E_F\simeq 1$ within the low temperature regime where this finding demonstrates that propagating modes of the Dirac fermions in this value reach at their minimum numbers and verifies the previous results for electronic conductance. We find that for thin widths of superconducting region, the thermal conductance vs temperature shows linear increment i.e. $\Gamma\varpropto T$. At last we propose an experimental set-up to detect our predicted effects.