Multiband strong-coupling superconductors with spontaneously broken time-reversal symmetry
| Autor: | Aase, Niels Henrik, Mæland, Kristian, Sudbø, Asle |
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| Rok vydání: | 2023 |
| Předmět: | |
| Zdroj: | Phys. Rev. B 108, 214508 (2023) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevB.108.214508 |
| Popis: | We study superconducting three-band systems within strong-coupling Eliashberg theory. In particular, we search for phase-frustrated superconducting systems with spontaneous time-reversal symmetry breaking (TRSB) states. The emergence of TRSB states in multiband systems has so far been studied using microscopic weak-coupling BCS theory or more phenomenological effective field theories such as multi-component Ginzburg-Landau theories. For systems with three disjoint Fermi surfaces whose electrons experience interactions mediated by phonons, we present a microscopic analysis showing that TRSB states also exist within a strong-coupling microscopic theory. The systems we consider have sizable electron-phonon couplings, putting them into the strong-coupling regime. They are thus a fitting description for strong-coupling materials such as some of the iron pnictides. Moreover, as the TRSB states are challenging to find numerically, we calculate the free energy of multiband systems within strong-coupling theory and make explicit use of it to pin down the TRSB states' elusive nature. Since Eliashberg theory is well incorporated with first-principles calculations, our strong-coupling approach might help facilitate a more efficient search for candidate materials that can exhibit TRSB. Comment: 15 pages, 6 figures |
| Databáze: | arXiv |
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