Two-channel Kondo phases and frustration-induced transitions in triple quantum dots
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 env...
| Main Authors: | , |
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| Format: | Journal article |
| Language: | English |
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2010
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| _version_ | 1826299397701369856 |
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| author | Mitchell, A Logan, D |
| author_facet | Mitchell, A Logan, D |
| author_sort | Mitchell, A |
| collection | OXFORD |
| description | 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. Two-channel Kondo (2CK) 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. © 2010 The American Physical Society. |
| first_indexed | 2024-03-07T05:01:20Z |
| format | Journal article |
| id | oxford-uuid:d86169c8-0670-4ec5-b278-d30175d636f4 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T05:01:20Z |
| publishDate | 2010 |
| record_format | dspace |
| spelling | oxford-uuid:d86169c8-0670-4ec5-b278-d30175d636f42022-03-27T08:48:08ZTwo-channel Kondo phases and frustration-induced transitions in triple quantum dotsJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:d86169c8-0670-4ec5-b278-d30175d636f4EnglishSymplectic Elements at Oxford2010Mitchell, ALogan, DWe 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. Two-channel Kondo (2CK) 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. © 2010 The American Physical Society. |
| spellingShingle | Mitchell, A Logan, D Two-channel Kondo phases and frustration-induced transitions in triple quantum dots |
| title | Two-channel Kondo phases and frustration-induced transitions in triple quantum dots |
| title_full | Two-channel Kondo phases and frustration-induced transitions in triple quantum dots |
| title_fullStr | Two-channel Kondo phases and frustration-induced transitions in triple quantum dots |
| title_full_unstemmed | Two-channel Kondo phases and frustration-induced transitions in triple quantum dots |
| title_short | Two-channel Kondo phases and frustration-induced transitions in triple quantum dots |
| title_sort | two channel kondo phases and frustration induced transitions in triple quantum dots |
| work_keys_str_mv | AT mitchella twochannelkondophasesandfrustrationinducedtransitionsintriplequantumdots AT logand twochannelkondophasesandfrustrationinducedtransitionsintriplequantumdots |