Undamped Higgs Modes in Strongly Interacting Superconductors
In superconductors, gauge <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>U</mi><mo>(</mo><mn>1</mn><mo>)</mo></mrow></semantics></math>...
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2024-09-01
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| author | José Lorenzana Götz Seibold |
| author_facet | José Lorenzana Götz Seibold |
| author_sort | José Lorenzana |
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| description | In superconductors, gauge <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>U</mi><mo>(</mo><mn>1</mn><mo>)</mo></mrow></semantics></math></inline-formula> symmetry is spontaneously broken. According to Goldstone’s theorem, this breaking of a continuous symmetry establishes the existence of the Bogoliubov phase mode while the gauge-invariant response also includes the amplitude fluctuations of the order parameter. The latter, which are also termed ‘Higgs’ modes in analogy with the standard model, appear at the energy of the spectral gap <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>2</mn><mo>Δ</mo></mrow></semantics></math></inline-formula>, when the superconducting ground state is evaluated within the weak-coupling BCS theory, and, therefore, are damped. Previously, we have shown that, within the time-dependent Gutzwiller approximation (TDGA), Higgs modes appear inside the gap with a finite binding energy relative to the quasiparticle continuum. Here, we show that the binding energy of the Higgs mode becomes exponentially small in the weak-coupling limit converging to the BCS solution. On the other hand, well-defined undamped amplitude modes exist in strongly coupled superconductors when the interaction energy becomes of the order of the bandwidth. |
| format | Article |
| id | doaj-art-565a93a85b974a2a9f1c8082b39c335b |
| institution | Kabale University |
| issn | 2410-3896 |
| language | English |
| publishDate | 2024-09-01 |
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| series | Condensed Matter |
| spelling | doaj-art-565a93a85b974a2a9f1c8082b39c335b2024-12-27T14:19:07ZengMDPI AGCondensed Matter2410-38962024-09-01943810.3390/condmat9040038Undamped Higgs Modes in Strongly Interacting SuperconductorsJosé Lorenzana0Götz Seibold1Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, Via dei Taurini 19, 00185 Roma, ItalyInstitut für Physik, Brandenburg Technical University Cottbus-Senftenberg, D-03013 Cottbus, GermanyIn superconductors, gauge <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>U</mi><mo>(</mo><mn>1</mn><mo>)</mo></mrow></semantics></math></inline-formula> symmetry is spontaneously broken. According to Goldstone’s theorem, this breaking of a continuous symmetry establishes the existence of the Bogoliubov phase mode while the gauge-invariant response also includes the amplitude fluctuations of the order parameter. The latter, which are also termed ‘Higgs’ modes in analogy with the standard model, appear at the energy of the spectral gap <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>2</mn><mo>Δ</mo></mrow></semantics></math></inline-formula>, when the superconducting ground state is evaluated within the weak-coupling BCS theory, and, therefore, are damped. Previously, we have shown that, within the time-dependent Gutzwiller approximation (TDGA), Higgs modes appear inside the gap with a finite binding energy relative to the quasiparticle continuum. Here, we show that the binding energy of the Higgs mode becomes exponentially small in the weak-coupling limit converging to the BCS solution. On the other hand, well-defined undamped amplitude modes exist in strongly coupled superconductors when the interaction energy becomes of the order of the bandwidth.https://www.mdpi.com/2410-3896/9/4/38superconductivitytime-dependent Gutzwillercollective modes |
| spellingShingle | José Lorenzana Götz Seibold Undamped Higgs Modes in Strongly Interacting Superconductors Condensed Matter superconductivity time-dependent Gutzwiller collective modes |
| title | Undamped Higgs Modes in Strongly Interacting Superconductors |
| title_full | Undamped Higgs Modes in Strongly Interacting Superconductors |
| title_fullStr | Undamped Higgs Modes in Strongly Interacting Superconductors |
| title_full_unstemmed | Undamped Higgs Modes in Strongly Interacting Superconductors |
| title_short | Undamped Higgs Modes in Strongly Interacting Superconductors |
| title_sort | undamped higgs modes in strongly interacting superconductors |
| topic | superconductivity time-dependent Gutzwiller collective modes |
| url | https://www.mdpi.com/2410-3896/9/4/38 |
| work_keys_str_mv | AT joselorenzana undampedhiggsmodesinstronglyinteractingsuperconductors AT gotzseibold undampedhiggsmodesinstronglyinteractingsuperconductors |