Thermoelectric Transport through a Quantum Dot: Effects of Kondo Channels Asymmetry

TL;DR

This paper investigates how magnetic fields influence thermoelectric properties of a quantum dot system, revealing new energy scales and a crossover between non-Fermi-liquid and Fermi-liquid behaviors related to Kondo effects.

Contribution

It introduces the effects of magnetic field on thermopower and conductance in a quantum dot, identifying new energy scales and describing the crossover between different Kondo regimes.

Findings

Identification of two new energy scales T_{min} and T_{max}

Prediction of Fermi-liquid behavior at low temperatures

Observation of crossover from non-Fermi-liquid to Fermi-liquid regimes

Abstract

We consider effects of magnetic field on the thermopower and thermoconductance of a single-electron transistor based on a quantum dot strongly coupled to one of the leads by a single-mode quantum point contact. We show appearance of two new energy scales: T_{min} ~ |r|^2 E_C(B/B_C)^2 depending on a ratio of magnetic field B and the field B_C corresponding to a full polarization of point contact and T_{max} ~ |r|^2 E_C depending on a reflection amplitude r and charging energy E_C. We predict that the behavior of thermoelectric coefficients is consistent with the Fermi-liquid theory at temperatures T << T_{min}, while crossover from Non-Fermi-liquid regime associated with a two-channel Kondo effect to Fermi-liquid single-channel Kondo behavior can be seen at T_{min}<T<T_{max}.