Common non-Fermi liquid phases in quantum impurity physics
We study correlated quantum impurity models which undergo a local quantum phase transition (QPT) from a strong coupling, Fermi liquid phase to a non-Fermi liquid phase with a globally doubly degenerate ground state. Our aim is to establish what can be shown exactly about such `local moment' (LM...
| Үндсэн зохиолчид: | , , |
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| Формат: | Journal article |
| Хэвлэсэн: |
2014
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| _version_ | 1826271654237437952 |
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| author | Logan, D Tucker, A Galpin, MR |
| author_facet | Logan, D Tucker, A Galpin, MR |
| author_sort | Logan, D |
| collection | OXFORD |
| description | We study correlated quantum impurity models which undergo a local quantum phase transition (QPT) from a strong coupling, Fermi liquid phase to a non-Fermi liquid phase with a globally doubly degenerate ground state. Our aim is to establish what can be shown exactly about such `local moment' (LM) phases; of which the permanent (zero-field) local magnetization is a hallmark, and an order parameter for the QPT. A description of the zero-field LM phase is shown to require two distinct self-energies, which reflect the broken symmetry nature of the phase and together determine the single self-energy of standard field theory. Distinct Friedel sum rules for each phase are obtained, via a Luttinger theorem embodied in the vanishing of appropriate Luttinger integrals. By contrast, the standard Luttinger integral is non-zero in the LM phase, but found to have universal magnitude. A range of spin susceptibilites are also considered; including that corresponding to the local order parameter, whose exact form is shown to be RPA-like, and to diverge as the QPT is approached. Particular attention is given to the pseudogap Anderson model, including the basic physical picture of the transition, the low-energy behavior of single-particle dynamics, the quantum critical point itself, and the rather subtle effect of an applied local field. A two-level impurity model which undergoes a QPT (`singlet-triplet') to an underscreened LM phase is also considered, for which we derive on general grounds some key results for the zero-bias conductance in both phases. |
| first_indexed | 2024-03-06T22:00:04Z |
| format | Journal article |
| id | oxford-uuid:4e473f41-baa7-4fa5-a994-776f29eacc7c |
| institution | University of Oxford |
| last_indexed | 2024-03-06T22:00:04Z |
| publishDate | 2014 |
| record_format | dspace |
| spelling | oxford-uuid:4e473f41-baa7-4fa5-a994-776f29eacc7c2022-03-26T16:00:16ZCommon non-Fermi liquid phases in quantum impurity physicsJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:4e473f41-baa7-4fa5-a994-776f29eacc7cSymplectic Elements at Oxford2014Logan, DTucker, AGalpin, MRWe study correlated quantum impurity models which undergo a local quantum phase transition (QPT) from a strong coupling, Fermi liquid phase to a non-Fermi liquid phase with a globally doubly degenerate ground state. Our aim is to establish what can be shown exactly about such `local moment' (LM) phases; of which the permanent (zero-field) local magnetization is a hallmark, and an order parameter for the QPT. A description of the zero-field LM phase is shown to require two distinct self-energies, which reflect the broken symmetry nature of the phase and together determine the single self-energy of standard field theory. Distinct Friedel sum rules for each phase are obtained, via a Luttinger theorem embodied in the vanishing of appropriate Luttinger integrals. By contrast, the standard Luttinger integral is non-zero in the LM phase, but found to have universal magnitude. A range of spin susceptibilites are also considered; including that corresponding to the local order parameter, whose exact form is shown to be RPA-like, and to diverge as the QPT is approached. Particular attention is given to the pseudogap Anderson model, including the basic physical picture of the transition, the low-energy behavior of single-particle dynamics, the quantum critical point itself, and the rather subtle effect of an applied local field. A two-level impurity model which undergoes a QPT (`singlet-triplet') to an underscreened LM phase is also considered, for which we derive on general grounds some key results for the zero-bias conductance in both phases. |
| spellingShingle | Logan, D Tucker, A Galpin, MR Common non-Fermi liquid phases in quantum impurity physics |
| title | Common non-Fermi liquid phases in quantum impurity physics |
| title_full | Common non-Fermi liquid phases in quantum impurity physics |
| title_fullStr | Common non-Fermi liquid phases in quantum impurity physics |
| title_full_unstemmed | Common non-Fermi liquid phases in quantum impurity physics |
| title_short | Common non-Fermi liquid phases in quantum impurity physics |
| title_sort | common non fermi liquid phases in quantum impurity physics |
| work_keys_str_mv | AT logand commonnonfermiliquidphasesinquantumimpurityphysics AT tuckera commonnonfermiliquidphasesinquantumimpurityphysics AT galpinmr commonnonfermiliquidphasesinquantumimpurityphysics |