RKKY interaction and local density of states for a triangular triple quantum dot system

Xiong, Yong‐Chen; Wang, Weizhong; Luo, Shijun; Yang, Juntao; Huang, Hongkun

doi:10.1016/j.jmmm.2015.09.021

Cited by 10 publications

(3 citation statements)

References 43 publications

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“…Among these geometries, the parallel TQD system is a basic structure, within which the Ruderman-Kittel-Kasuya-Yosida (RKKY) exchange interaction becomes one of the most important element. In particular, the RKKY interaction depends closely on the interdot distance and is always mediated by the Kondo exchange interaction between conduction electrons and those located in the dots [19,47], as well as the interdot electron hopping [28,53]. However, in this paper, we find the RKKY interaction is invalid in parallel TQD system when the level spacings between different dots are adjusted in appropriate regime.…”

Section: Introductionmentioning

confidence: 64%

Suppressed Kondo effect and Kosterlitz–Thouless-type phase transition induced by level difference in a triple dot device

Xiong

Huang

Zhao

et al. 2017

J. Phys.: Condens. Matter

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Quantum dot system provides an ideal platform for quantum information processing, within which to demonstrate the quantum states is one of the most important issue for quantum simulation and quantum computation. In this paper, we report a peculiar electron state in a parallel triple dot device where the Ruderman-Kittel-Kasuya-Yosida interaction is invalid when the level differences of the dots sweep into appropriate regime. This extraordinary tendency then results in an antiferromagnetic spin coupling between two of the dots and may lead to zero or full conductance, relying deeply on the relation of the two level spacings. e.g. when the level differences are kept equal, the Kondo effect is totally suppressed although the dots are triply occupied, since in this case a local inter-dot transport loop is found to play an important role in the transmission coefficient. By contrast, when the differences are retained symmetric, the Kondo peak reaches nearly to its unitary limit, owing to that the inter-dot transport process is significantly suppressed. To approach these problems, voltage controllable quantum phase transitions of Kosterlitz-Thouless type and first order are shown, and possible pictures related to the many-body effect and the effective Kondo model are given.

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Section: Introductionmentioning

confidence: 64%

Suppressed Kondo effect and Kosterlitz–Thouless-type phase transition induced by level difference in a triple dot device

Xiong

Huang

Zhao

et al. 2017

J. Phys.: Condens. Matter

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“…[17,18] While in the theoretical field, TQD structure offers the potential to study some new fascinating phenomena at low temperatures, including the Kondo effect, [19][20][21][22] the Fermi liquid theory, [23,24] the quantum interference, [25,26] and various kinds of quantum phase transitions (QPT). [27][28][29][30][31] TQD structure could be organized in serial, [32,33] parallel, [34][35][36] or triangular [37][38][39][40] spatial configuration, which may naturally result in different quantum behaviors. Among these configurations, the parallel TQD (PTQD) system is a basic one, which has also inspired a wealth of research.…”

Section: Introductionmentioning

confidence: 99%

Phase transition and charge transport through a triple dot device beyond the Kondo regime

Xiong¹,

Zhu²,

He³

2018

Chinese Phys. B

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Semiconductor quantum dot structure provides a promising basis for quantum information processing, within which to reveal the quantum phase and charge transport is one of the most important issues. In this paper, by means of the numerical renormalization group technique, we study the quantum phase transition and the charge transport for a parallel triple dot device in the strongly correlated limit, focusing on the effect of inter-dot hopping t beyond the Kondo regime. We find the quantum behaviors depend closely on the initial electron number on the dots, and the present model may map to single, double, and side-coupled impurity models in different parameter spaces. An orbital spin-1/2 Kondo effect between the conduction leads and the bonding orbital, and several magnetic-frustration phases are demonstrated when t is adjusted to different regimes. To understand these phenomena, a canonical transformation of the energy levels is given, and important physical quantities with respect to increasing t and necessary theoretical discussions are shown.

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“…For instance, the Aharanov-Bohm (AB) effect and magnetic frustration are studied in systems with triangular geometry, [12][13][14][15] and the multi-channel Kondo effect related to a number of Fermi-liquid and non-Fermi-liquid behaviors are investigated in various TQD models. [16][17][18][19][20] Furthermore, TQD systems are also considered as ideal models to show the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction, [21,22] the quantum interference, [23][24][25][26] and various kinds of quantum phase transition (QPT). [13,15,[27][28][29][30][31][32] Basically, these behaviors depend closely on the organizations of the quantum dots and the conduction leads, as well as the coupling/interaction elements which have been taken into account.…”

Section: Introductionmentioning

confidence: 99%

Voltage-controlled Kosterlitz–Thouless transitions and various kinds of Kondo behaviors in a triple dot device

Xiong¹,

Zhang²,

Zhou³

et al. 2017

Chinese Phys. B

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The transport property and phase transition for a parallel triple dot device are studied by adopting Wilson's numerical renormalization group technique, focusing on the effects of level spacings between neighboring dot sites. By keeping dot 2 at the half-filled level and tuning the level differences, it is demonstrated that the system transits from local spin quadruplet to triplet and doublet sequently, and three kinds of Kondo peaks at the Fermi surface could be found, which are separated by two Kosterlitz-Thouless type quantum phase transitions and correspond to spin-3/2, spin-1, and spin-1/2 Kondo effect, respectively. To obtain a detailed understanding of these problems, the charge occupation, the spin-spin correlation, the transmission coefficient, and the temperature-dependent magnetic moment are shown, and necessary physical arguments are given.

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RKKY interaction and local density of states for a triangular triple quantum dot system

Cited by 10 publications

References 43 publications

Suppressed Kondo effect and Kosterlitz–Thouless-type phase transition induced by level difference in a triple dot device

Suppressed Kondo effect and Kosterlitz–Thouless-type phase transition induced by level difference in a triple dot device

Phase transition and charge transport through a triple dot device beyond the Kondo regime

Voltage-controlled Kosterlitz–Thouless transitions and various kinds of Kondo behaviors in a triple dot device

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