Conductance through Quantum Dot Dimer Below the Kondo Temperature

Aono, Tomosuke; Eto, Mikio; Kawamura, Kiyoshi

doi:10.1143/jpsj.67.1860

Cited by 69 publications

(61 citation statements)

References 18 publications

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“…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.…”

Section: Introductionmentioning

confidence: 99%

Interference effects on Kondo-assisted transport through double quantum dots

2005

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We systematically investigate electron transport through double quantum dots with particular emphasis on interference induced via multiple paths of electron propagation. By means of the slave-boson mean-field approximation, we calculate the conductance, the local density of states, the transmission probability in the Kondo regime at zero temperature. It is clarified how the Kondoassisted transport changes its properties when the system is continuously changed among the serial, parallel and T-shaped double dots. The obtained results for the conductance are explained in terms of the Kondo resonances influenced by interference effects. We also discuss the impacts due to the spin-polarization of ferromagnetic leads.

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Section: Introductionmentioning

confidence: 99%

Interference effects on Kondo-assisted transport through double quantum dots

2005

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“…The relevance of the Kondo effect in the double dot system has been studied in [15,16]. Here, we focus on the competition between the Kondo effect and antiferromagnetic exchange, and present detailed predictions for the conductance.…”

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confidence: 99%

Electronic Correlations in Transport through Coupled Quantum Dots

1999

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The conductance through two quantum dots in series is studied using general qualitative arguments and quantitative slave-boson mean-field theory. It is demonstrated that measurements of the conductance can explore the phase diagram of the two-impurity Anderson model. Competition between the Kondo effect and the inter-dot magnetic exchange leads to a two-plateau structure in the conductance as a function of gate voltage and a two or three peak structure in the conductance vs. inter-dot tunneling.Pacs numbers: 73.40Gk, 72.15Qm, 73.23.Hk The recent observation of the Kondo effect in transport through a quantum dot [1-3] opened a new path for the investigations of strongly correlated electrons. Having confirmed earlier theoretical predictions [4,5], that a quantum dot behaves as a magnetic impurity, these experiments also serve as a critical quantitative test for existing theories. In particular, unlike magnetic impurities in metals which have physical properties determined by the host metal and the impurity atom, the corresponding parameters in the quantum dot case can be varied continuously, enabling, for example, a crossover from the Kondo to the mixed-valence and the empty dot regimes in the same sample [1,2].The behavior of a lattice of magnetic impurities, such as a heavy-fermion system, is characterized by the competition between the Kondo effect and the magnetic correlations between the impurities. An important step towards the understanding of this problem was taken by Jones and collaborators [6], who studied the two-impurity problem. Their work demonstrated that this competition leads to a second-order phase transition when particlehole symmetry applies. When this symmetry is broken, this transition is replaced by a crossover [7][8][9]. In view of the extensive experimental research on transport through two dots in series [10,11], it is thus natural to try and understand how this phase-transition is manifested in the double-dot system, both because such systems may have important applications (such as a quantum-dot laser [12]), and because such a tunable system may reveal detailed information on the corresponding phase diagram.Transport through a double-dot system (see inset in Fig. 1) has already received much theoretical attention, in particular in the high temperature, Coulomb blockaded regime [12,13]. In experiments the Coulomb charging energy and the excitation energy are much larger than temperature. Accordingly, only a single state on each dot is important, and double occupancy of each dot can be ignored. Denoting the energies of these states by ǫ 1 ≡ ǫ 0 + ∆ǫ and ǫ 2 ≡ ǫ 0 − ∆ǫ, respectively, and the tunneling amplitude between the dots by t, the isolated double dot system can contain zero, one or two electrons, depending on the chemical potential: N = 0 for µ < ǫ − , N = 1 for ǫ − < µ < ǫ + , and N = 2 for µ > ǫ + , with ǫ ± = ǫ 0 ± √ ∆ǫ 2 + t 2 . In the presence of a finite antiferromagnetic spin-exchange J between the dots, one still has the above three possibilities with ǫ + replaced by ǫ + ...

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“…The corresponding critical superexchange interaction is of the order of Kondo temperature as before, J c ∼ 2T K . As discussed above, in this regime each of the dots undergoes the Kondo effect where local moment is screened by conducting electrons in the adjacent lead and left -right sides of the system become decoupled which leads to vanishing A→B conductance as G ∝ (t/Γ ) 2 [19].…”

Section: Conductancementioning

confidence: 98%