A Model for Two-Channel Kondo Effect in CNT Quantum Dot

TL;DR

This paper models the two-channel Kondo effect in carbon nanotube quantum dots with a spin-1/2 atom, revealing a non-monotonic conductance behavior due to two distinct scaling regimes.

Contribution

It introduces a model utilizing the two valleys in CNTs as flavor quantum numbers to demonstrate the two-channel Kondo effect with a finite weak-coupling fixed point.

Findings

Kondo temperature estimated between 0.5 and 5 K

Finite weak-coupling two-channel fixed point identified

Non-monotonic conductance dependence on temperature

Abstract

Over-screened Kondo effect is feasible in carbon nanotube quantum dot junction hosting a spin $\tfrac{1}{2}$ atom with single $s$-wave valence electron (e.g Au). The idea is to use the two valleys as two symmetry protected flavor quantum numbers $\xi={\bf K}, {\bf K}'$. Perturbative RG analysis exposes the finite weak-coupling two-channel fixed point, where the Kondo temperature is estimated to be around $0.5\div5$~K. Remarkably, occurrence of two different scaling regimes implies a non-monotonic dependence of the conductance as function of temperature.