Thermal conductance by Dirac fermions in a normal-insulator-superconductor junction of silicene

TL;DR

This paper investigates the thermal conductance behavior in silicene-based normal-insulator-superconductor junctions, revealing oscillatory patterns influenced by barrier properties, doping, and external electric fields, with potential to identify Andreev reflection regimes.

Contribution

It introduces a theoretical analysis of thermal conductance oscillations in silicene junctions, highlighting the effects of barrier strength, doping, and electric fields, and proposes a method to probe Andreev reflection crossover.

Findings

Thermal conductance shows exponential temperature dependence.

Oscillatory dependence on barrier strength and thickness.

Doping alters the periodicity of conductance oscillations.

Abstract

We theoretically study the properties of thermal conductance in a normal-insulator-superconductor junction of silicene for both thin and thick barrier limit. We show that while thermal conductance displays the conventional exponential dependence on temperature, it manifests a nontrivial oscillatory dependence on the strength of the barrier region. The tunability of the thermal conductance by an external electric field is also investigated. Moreover, we explore the effect of doping concentration on thermal conductance. In the thin barrier limit, the period of oscillations of the thermal conductance as a function of the barrier strength comes out be $\pi/2$ when doping concentration in the normal silicene region is small. On the other hand, the period gradually converts to $\pi$ with the enhancement of the doping concentration. Such change of periodicity of the thermal response with doping can be a possible probe to identify the crossover from specular to retro Andreev reflection in Dirac materials. In the thick barrier limit, thermal conductance exhibits oscillatory behavior as a function of barrier thickness $d$ and barrier height $V_0$ while the period of oscillation becomes $V_0$ dependent. However, amplitude of the oscillations, unlike in tunneling conductance, gradually decays with the increase of barrier thickness for arbitrary height $V_0$ in the highly doped regime. We discuss experimental relevance of our results.