Noncontractible loop states from a partially flat band in a photonic borophene lattice
Flat band systems are commonly associated with compact localized states (CLSs) that arise from the macroscopic degeneracy of eigenstates at the flat band energy. However, in the case of singular flat bands, conventional localized flat band states are incomplete, leading to the existence of noncontra...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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De Gruyter
2023-07-01
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| Series: | Nanophotonics |
| Subjects: | |
| Online Access: | https://doi.org/10.1515/nanoph-2023-0222 |
| _version_ | 1797740365801848832 |
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| author | Menz Philip Hanafi Haissam Imbrock Jörg Denz Cornelia |
| author_facet | Menz Philip Hanafi Haissam Imbrock Jörg Denz Cornelia |
| author_sort | Menz Philip |
| collection | DOAJ |
| description | Flat band systems are commonly associated with compact localized states (CLSs) that arise from the macroscopic degeneracy of eigenstates at the flat band energy. However, in the case of singular flat bands, conventional localized flat band states are incomplete, leading to the existence of noncontractible loop states (NLSs) with nontrivial real-space topology. In this study, we experimentally and analytically demonstrate the existence of NLSs in a 2D photonic borophene lattice without a CLS counterpart, owing to a band that is flat only along high-symmetry lines and dispersive along others. Our findings challenge the conventional notion that NLSs are necessarily linked to robust boundary modes due to a bulk-boundary correspondence. Protected by the band flatness that originates from band touching, NLSs play a significant role in investigating the fundamental physics of flat band systems. |
| first_indexed | 2024-03-12T14:11:24Z |
| format | Article |
| id | doaj.art-2632a2088f0447e1a8ba908b4e98a1c5 |
| institution | Directory Open Access Journal |
| issn | 2192-8614 |
| language | English |
| last_indexed | 2024-03-12T14:11:24Z |
| publishDate | 2023-07-01 |
| publisher | De Gruyter |
| record_format | Article |
| series | Nanophotonics |
| spelling | doaj.art-2632a2088f0447e1a8ba908b4e98a1c52023-08-21T06:42:27ZengDe GruyterNanophotonics2192-86142023-07-0112173409341510.1515/nanoph-2023-0222Noncontractible loop states from a partially flat band in a photonic borophene latticeMenz Philip0Hanafi Haissam1Imbrock Jörg2Denz Cornelia3Institute of Applied Physics, University of Münster, Münster, GermanyInstitute of Applied Physics, University of Münster, Münster, GermanyInstitute of Applied Physics, University of Münster, Münster, GermanyInstitute of Applied Physics, University of Münster, Münster, GermanyFlat band systems are commonly associated with compact localized states (CLSs) that arise from the macroscopic degeneracy of eigenstates at the flat band energy. However, in the case of singular flat bands, conventional localized flat band states are incomplete, leading to the existence of noncontractible loop states (NLSs) with nontrivial real-space topology. In this study, we experimentally and analytically demonstrate the existence of NLSs in a 2D photonic borophene lattice without a CLS counterpart, owing to a band that is flat only along high-symmetry lines and dispersive along others. Our findings challenge the conventional notion that NLSs are necessarily linked to robust boundary modes due to a bulk-boundary correspondence. Protected by the band flatness that originates from band touching, NLSs play a significant role in investigating the fundamental physics of flat band systems.https://doi.org/10.1515/nanoph-2023-0222borophenecompact localized states (cls)flat bandnoncontractible loop states (nls)topological photonicswave localization |
| spellingShingle | Menz Philip Hanafi Haissam Imbrock Jörg Denz Cornelia Noncontractible loop states from a partially flat band in a photonic borophene lattice Nanophotonics borophene compact localized states (cls) flat band noncontractible loop states (nls) topological photonics wave localization |
| title | Noncontractible loop states from a partially flat band in a photonic borophene lattice |
| title_full | Noncontractible loop states from a partially flat band in a photonic borophene lattice |
| title_fullStr | Noncontractible loop states from a partially flat band in a photonic borophene lattice |
| title_full_unstemmed | Noncontractible loop states from a partially flat band in a photonic borophene lattice |
| title_short | Noncontractible loop states from a partially flat band in a photonic borophene lattice |
| title_sort | noncontractible loop states from a partially flat band in a photonic borophene lattice |
| topic | borophene compact localized states (cls) flat band noncontractible loop states (nls) topological photonics wave localization |
| url | https://doi.org/10.1515/nanoph-2023-0222 |
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