Chessboard magnetoconductance of a quantum dot in the Kondo regime

TL;DR

This paper provides a theoretical analysis of the chessboard pattern in magnetoconductance observed in quantum dots within the Kondo regime, revealing oscillations in Kondo temperature due to ground state changes.

Contribution

It introduces an effective Kondo Hamiltonian focusing on low-energy states, explaining the alternating conductance regions and oscillations in Kondo temperature.

Findings

Kondo temperature oscillates with magnetic field and electron number.

Ground states alternate between strong and weak correlation effects.

Effective antiferromagnetic exchange couplings depend on tunneling and correlations.

Abstract

Transport through a quantum dot (QD) in the Kondo regime shows alternating regions of high and low conductance when both an external magnetic field and the gate potential controlling the depth of the QD potential are varied. We present a theoretical analysis of this chessboard aspect of the magneto-conductance. An effective Kondo Hamiltonian is obtained by means of a restriction to the Hilbert space supported by just a few low energy states of N and N(+/-)1 electrons in the QD. We obtain antiferromagnetic exchange couplings depending on tunneling amplitudes and correlation effects. When either the magnetic field or the number of electrons in the QD is varied, Kondo temperature shows large oscillations due to the successive appearance of ground states having strong and weak correlation effects alternatively.