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).
Categories: cond-mat.other cond-mat.mes-hall