Flat-band ratio and quantum metric in the superconductivity of modified Lieb lattices
Abstract Flat bands may offer a route to high critical temperatures of superconductivity. It has been predicted that the quantum geometry of the bands as well as the ratio of the number of flat bands to the number of orbitals determine flat band superconductivity. However, such results have assumed...
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Nature Portfolio
2025-01-01
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| Series: | Communications Physics |
| Online Access: | https://doi.org/10.1038/s42005-025-01964-y |
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| author | Reko P. S. Penttilä Kukka-Emilia Huhtinen Päivi Törmä |
| author_facet | Reko P. S. Penttilä Kukka-Emilia Huhtinen Päivi Törmä |
| author_sort | Reko P. S. Penttilä |
| collection | DOAJ |
| description | Abstract Flat bands may offer a route to high critical temperatures of superconductivity. It has been predicted that the quantum geometry of the bands as well as the ratio of the number of flat bands to the number of orbitals determine flat band superconductivity. However, such results have assumed at least one of the following: an isolated flat band, zero temperature, mean-field theory, and/or uniform pairing. Here, we explore flat band superconductivity when these assumptions are relaxed. We consider an attractive Hubbard model for different extensions of the Lieb lattice. The superconducting order parameter, critical temperature, superfluid weight, and Berezinskii-Kosterlitz-Thouless (BKT) temperature are calculated within dynamical mean-field theory. We find that for isolated flat bands, the flat-band ratio and quantum geometry are in general good indicators of superconductivity even at finite temperatures. For non-isolated flat bands, a good guideline of the BKT temperature is provided by the zero-temperature superfluid weight and the flat-band ratio. |
| format | Article |
| id | doaj-art-5cd27c233259402f8897bd986f9bf273 |
| institution | Kabale University |
| issn | 2399-3650 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | Nature Portfolio |
| record_format | Article |
| series | Communications Physics |
| spelling | doaj-art-5cd27c233259402f8897bd986f9bf2732025-02-02T12:28:04ZengNature PortfolioCommunications Physics2399-36502025-01-018111010.1038/s42005-025-01964-yFlat-band ratio and quantum metric in the superconductivity of modified Lieb latticesReko P. S. Penttilä0Kukka-Emilia Huhtinen1Päivi Törmä2Department of Applied Physics, Aalto University School of ScienceDepartment of Applied Physics, Aalto University School of ScienceDepartment of Applied Physics, Aalto University School of ScienceAbstract Flat bands may offer a route to high critical temperatures of superconductivity. It has been predicted that the quantum geometry of the bands as well as the ratio of the number of flat bands to the number of orbitals determine flat band superconductivity. However, such results have assumed at least one of the following: an isolated flat band, zero temperature, mean-field theory, and/or uniform pairing. Here, we explore flat band superconductivity when these assumptions are relaxed. We consider an attractive Hubbard model for different extensions of the Lieb lattice. The superconducting order parameter, critical temperature, superfluid weight, and Berezinskii-Kosterlitz-Thouless (BKT) temperature are calculated within dynamical mean-field theory. We find that for isolated flat bands, the flat-band ratio and quantum geometry are in general good indicators of superconductivity even at finite temperatures. For non-isolated flat bands, a good guideline of the BKT temperature is provided by the zero-temperature superfluid weight and the flat-band ratio.https://doi.org/10.1038/s42005-025-01964-y |
| spellingShingle | Reko P. S. Penttilä Kukka-Emilia Huhtinen Päivi Törmä Flat-band ratio and quantum metric in the superconductivity of modified Lieb lattices Communications Physics |
| title | Flat-band ratio and quantum metric in the superconductivity of modified Lieb lattices |
| title_full | Flat-band ratio and quantum metric in the superconductivity of modified Lieb lattices |
| title_fullStr | Flat-band ratio and quantum metric in the superconductivity of modified Lieb lattices |
| title_full_unstemmed | Flat-band ratio and quantum metric in the superconductivity of modified Lieb lattices |
| title_short | Flat-band ratio and quantum metric in the superconductivity of modified Lieb lattices |
| title_sort | flat band ratio and quantum metric in the superconductivity of modified lieb lattices |
| url | https://doi.org/10.1038/s42005-025-01964-y |
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