Reversable heat flow through the carbon nanotube junctions

TL;DR

This paper presents a theoretical study of reversible heat flow in carbon nanotube junctions, highlighting electron and hole transport mechanisms influenced by bias voltages and explaining experimental sign reversals via chiral tunneling effects.

Contribution

It introduces a model explaining reversible heat flow through nanotube junctions, emphasizing the roles of ballistic charge carriers and chiral tunneling phenomena.

Findings

Heat transfer is driven by electrons and holes moving ballistically.

Seebeck coefficient, electrical and thermal conductivities depend on bias voltages.

Sign reversal of Seebeck coefficient explained by chiral tunneling (Klein paradox).

Abstract

Microscopic mechanisms of externally controlled reversable heat flow through the carbon nanotube junctions (NJ) are studied theoretically. Our model suggests that the heat is transfered along the tube section ${\cal T}$ by electrons ($e$) and holes ($h$) moving ballistically in either in parallel or in opposite directions and accelerated by the bias source-drain voltage $V_{\rm SD}$ (Peltier effect). We compute the Seebeck coefficient $\alpha $, electric $\sigma$ and thermal $\kappa$ conductivities and find that their magnitudes strongly depend on $V_{\rm SD}$ and $V_{\rm G}$. The sign reversal of $\alpha$ versus the sign of $V_{\rm G}$ formerly observed experimentally is interpreted in this work in terms of so-called chiral tunneling phenomena (Klein paradox).