Tunneling through triple quantum dots with mirror symmetry

Kuzmenko, Tetyana; Kikoin, K.; Avishai, Y.

doi:10.1103/physrevb.73.235310

Cited by 44 publications

(52 citation statements)

References 35 publications

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“…In mirror-symmetric systems, all dot states can be classified by their parity under left↔ right interchange. 11,13 This symmetry permits a level crossing of states in the isolated trimer on varying the interdot couplings, with a pair of degenerate doublets comprising the ground state when all dots are equivalent. It was recently shown 13 that this level-crossing is preserved in the full many-body system when a single lead is attached.…”

Section: Introductionmentioning

confidence: 98%

Two-channel Kondo phases and frustration-induced transitions in triple quantum dots

Mitchell

Logan

2010

Phys. Rev. B

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We study theoretically a ring of three quantum dots mutually coupled by antiferromagnetic exchange interactions and tunnel-coupled to two metallic leads: the simplest model in which the consequences of local frustration arising from internal degrees of freedom may be studied within a two-channel environment. Twochannel Kondo ͑2CK͒ physics is found to predominate at low energies in the mirror-symmetric models considered, with a residual spin-1 2 overscreened by coupling to both leads. It is however shown that two distinct 2CK phases, with different ground-state parities, arise on tuning the interdot exchange couplings. In consequence a frustration-induced quantum phase transition occurs, the 2CK phases being separated by a quantum critical point for which an effective low-energy model is derived. Precisely at the transition, parity mixing of the quasidegenerate local trimer states acts to destabilize the 2CK fixed points; and the critical fixed point is shown to consist of a free pseudospin together with effective one-channel spin quenching, itself reflecting underlying channel anisotropy in the inherently two-channel system. Numerical renormalization group techniques and physical arguments are used to obtain a detailed understanding of the problem, including study of both thermodynamic and dynamical properties of the system.

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Section: Introductionmentioning

confidence: 98%

Two-channel Kondo phases and frustration-induced transitions in triple quantum dots

Mitchell

Logan

2010

Phys. Rev. B

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“…21 The usual Kondo physics combines spin and charge degrees of freedom and can be extended to a number of electron occupation configurations across the TQD. [29][30][31] Several efforts have been undertaken to produce laterally defined TQDs. In an early attempt, large TQDs in a serial configuration were studied via transport measurements as a function of the coupling between the QDs.…”

Section: Introductionmentioning

confidence: 99%

Electrostatically defined serial triple quantum dot charged with few electrons

et al. 2007

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A serial triple quantum dot ͑TQD͒ electrostatically defined in a GaAs/ AlGaAs heterostructure is characterized by using a nearby quantum point contact as charge detector. Ground-state stability diagrams demonstrate control in the regime of few electrons charging the TQD. An electrostatic model is developed to determine the ground-state charge configurations of the TQD. Numerical calculations are compared with experimental results. In addition, the tunneling conductance through all three quantum dots in series is studied. Quantum cellular automata processes are identified, which are where charge reconfiguration between two dots occurs in response to the addition of an electron in the third dot.

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“…Very recently transport properties of triple quantum dots have become a subject of intensive studies due to various interesting effects that emerge in such structures [32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50]. In particular, triple dots enable the investigation of spin-entangled currents [32], dark states [37,41], or various interference effects [34,39].…”

Section: Introductionmentioning

confidence: 99%

The tunnel magnetoresistance in chains of quantum dots weakly coupled to external leads

Weymann

2009

J. Phys.: Condens. Matter

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Abstract. We analyze numerically the spin-dependent transport through coherent chains of three coupled quantum dots weakly connected to external magnetic leads. In particular, using the diagrammatic technique on the Keldysh contour, we calculate the conductance, shot noise and tunnel magnetoresistance (TMR) in the sequential and cotunneling regimes. We show that transport characteristics greatly depend on the strength of the interdot Coulomb correlations, which determines the spacial distribution of electron wave function in the chain. When the correlations are relatively strong, depending on the transport regime, we find both negative TMR as well as TMR enhanced above the Julliere value, accompanied with negative differential conductance (NDC) and super-Poissonian shot noise. This nontrivial behavior of tunnel magnetoresistance is associated with selection rules that govern tunneling processes and various high-spin states of the chain that are relevant for transport. For weak interdot correlations, on the other hand, the TMR is always positive and not larger than the Julliere TMR, although super-Poissonian shot noise and NDC can still be observed.

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Tunneling through triple quantum dots with mirror symmetry

Cited by 44 publications

References 35 publications

Two-channel Kondo phases and frustration-induced transitions in triple quantum dots

Two-channel Kondo phases and frustration-induced transitions in triple quantum dots

Electrostatically defined serial triple quantum dot charged with few electrons

The tunnel magnetoresistance in chains of quantum dots weakly coupled to external leads

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