Transport in coupled quantum dots: Kondo effect versus antiferromagnetic correlation

Abstract

The interplay between the Kondo effect and the inter-dot magnetic interaction in a coupled-dot system is studied. An exact result for the transport properties at zero temperature is obtained by diagonalizing a cluster, composed by the double-dot and its vicinity, which is connected to leads. It is shown that the system goes continuously from the Kondo regime to an anti-ferromagnetic state as the inter-dot interaction is increased. The conductance, the charge at the dots and the spin-spin correlation are obtained as a function of the gate potential.

Interference effects on Kondo-assisted transport through double quantum dots

“…There have been a number of theoretical works on DQD systems in this context. For example, it was pointed out that the DQD system shows the dramatic suppression of the Kondo-assisted transport due to the interference when the DQD is arranged in the parallel geometry [15,16,17,18,19,20,21,22], whereas such interference effects do not appear in the serial DQD [16,23,24,25,26,27,28,29,30]. More recently, slightly different DQD systems with the parallel geometry, where the two dots are connected via the exchange coupling [19] or the tunneling [20,21], have been studied.…”

Swapping Kondo resonances in coupled double quantum dots

“…The Kondo effect for even number electrons on a single multilevel dot and possible phase transitions between singlet and triplet states have been considered for both "vertical" [5] and "lateral" [6,7,8,9] configurations. For the coupled DQD with degenerate energy levels, the Kondo behavior and the ISS interplay and strongly compete, as seen in the bulk two-impurity Kondo problem,[10] and a question arises whether there exists a spin entangled state composed of the coherent Kondo resonances.[11] Previous experimental and theoretical studies have mainly focused on the serial-coupled DQD [12,13,14,15,16,17,18,19], except for Ref. 9, 19.…”

“…[11] Previous experimental and theoretical studies have mainly focused on the serial-coupled DQD [12,13,14,15,16,17,18,19], except for Ref. 9, 19.…”

“…For the coupled DQD with degenerate energy levels, the Kondo behavior and the ISS interplay and strongly compete, as seen in the bulk two-impurity Kondo problem, [10] and a question arises whether there exists a spin entangled state composed of the coherent Kondo resonances. [11] Previous experimental and theoretical studies have mainly focused on the serial-coupled DQD [12,13,14,15,16,17,18,19], except for Ref. 9,19.…”

Transport properties of a two-impurity system: A theoretical approach

“…3,4 From the theoretical point of view, numerical renormalization group (NRG) 7 calculations on the two-impurity Anderson model (TIAM) focused on the properties of its non-Fermi Liquid QCP 8 and pointed out that the interimpurity hopping suppresses the critical transition 9,10 . Several theoretical methods were used to analyze the TIAM, as the slave-boson formalism [11][12][13][14][15][16][17] , the NRG 8,18 , the Embedded Cluster Approximation (ECA) 19 , and the noncrossing approximation 20 . The results obtained confirmed the replacement of the critical transition by a crossover as a consequence of the broken evenodd parity symmetry.…”