Collective excitation spectrum of a disordered Hubbard model
We study the collective excitation spectrum of a d=3 site-disordered Anderson-Hubbard model at half-filling, via a random-phase approximation (RPA) about broken-symmetry, inhomogeneous unrestricted Hartree-Fock (UHF) ground states. We focus in particular on the density and character of low-frequency...
| Main Authors: | , , |
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| Format: | Journal article |
| Language: | English |
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1998
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| _version_ | 1797078382997929984 |
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| author | Szczech, Y Tusch, M Logan, D |
| author_facet | Szczech, Y Tusch, M Logan, D |
| author_sort | Szczech, Y |
| collection | OXFORD |
| description | We study the collective excitation spectrum of a d=3 site-disordered Anderson-Hubbard model at half-filling, via a random-phase approximation (RPA) about broken-symmetry, inhomogeneous unrestricted Hartree-Fock (UHF) ground states. We focus in particular on the density and character of low-frequency collective excitations in the transverse spin channel. In the absence of disorder, these are found to be spin-wave-like for all but very weak interaction strengths, extending down to zero frequency and separated from a Stoner-like band, to which there is a gap. With disorder present, a prominent spin-wave-like band is found to persist over a wide region of the disorder-interaction phase plane in which the mean-field ground state is a disordered antiferromagnet, despite the closure of the UHF single-particle gap. Site resolution of the RPA excitations leads to a microscopic rationalization of the evolution of the spectrum with disorder and interaction strength, and enables the observed localization properties to be interpreted in terms of the fraction of strong local moments and their site-differential distribution. |
| first_indexed | 2024-03-07T00:31:11Z |
| format | Journal article |
| id | oxford-uuid:7fda991d-b06d-4772-9b67-0c8bd241e71a |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T00:31:11Z |
| publishDate | 1998 |
| record_format | dspace |
| spelling | oxford-uuid:7fda991d-b06d-4772-9b67-0c8bd241e71a2022-03-26T21:19:29ZCollective excitation spectrum of a disordered Hubbard modelJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:7fda991d-b06d-4772-9b67-0c8bd241e71aEnglishSymplectic Elements at Oxford1998Szczech, YTusch, MLogan, DWe study the collective excitation spectrum of a d=3 site-disordered Anderson-Hubbard model at half-filling, via a random-phase approximation (RPA) about broken-symmetry, inhomogeneous unrestricted Hartree-Fock (UHF) ground states. We focus in particular on the density and character of low-frequency collective excitations in the transverse spin channel. In the absence of disorder, these are found to be spin-wave-like for all but very weak interaction strengths, extending down to zero frequency and separated from a Stoner-like band, to which there is a gap. With disorder present, a prominent spin-wave-like band is found to persist over a wide region of the disorder-interaction phase plane in which the mean-field ground state is a disordered antiferromagnet, despite the closure of the UHF single-particle gap. Site resolution of the RPA excitations leads to a microscopic rationalization of the evolution of the spectrum with disorder and interaction strength, and enables the observed localization properties to be interpreted in terms of the fraction of strong local moments and their site-differential distribution. |
| spellingShingle | Szczech, Y Tusch, M Logan, D Collective excitation spectrum of a disordered Hubbard model |
| title | Collective excitation spectrum of a disordered Hubbard model |
| title_full | Collective excitation spectrum of a disordered Hubbard model |
| title_fullStr | Collective excitation spectrum of a disordered Hubbard model |
| title_full_unstemmed | Collective excitation spectrum of a disordered Hubbard model |
| title_short | Collective excitation spectrum of a disordered Hubbard model |
| title_sort | collective excitation spectrum of a disordered hubbard model |
| work_keys_str_mv | AT szczechy collectiveexcitationspectrumofadisorderedhubbardmodel AT tuschm collectiveexcitationspectrumofadisorderedhubbardmodel AT logand collectiveexcitationspectrumofadisorderedhubbardmodel |