Chessboard magnetoconductance of a quantum dot in the Kondo regime

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.