Superconductivity via paramagnon and magnon exchange in a 2D near-ferromagnetic full metal and ferromagnetic half-metal
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| Format: | Preprint |
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2025
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| _version_ | 1866908442768179200 |
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| author | Raines, Zachary M Chubukov, Andrey V |
| author_facet | Raines, Zachary M Chubukov, Andrey V |
| contents | We study superconductivity in paramagnetic and ferromagnetically-ordered phases in a two-dimensional electron system with parabolic fermionic dispersion and short-range repulsive interaction. In the paramagnetic phase, we find that a weak momentum dependence of a paramagnon propagator parametrically reduces the onset temperature for the pairing compared to that in phenomenological theories which assume a strong dispersion of a paramagnon and also changes the topology of the gap function. In the ferromagnetic phase, we show that the order instantly polarizes low-energy fermionic excitations. We derive the fully renormalized pairing interaction between low-energy fermions, mediated by two transverse Goldstone modes and show that it is attractive in a spatially-odd channel. The pairing temperature in the ferromagnetic phase is found to be a fraction of the Fermi energy, significantly larger than in the paramagnetic phase near the transition. Our results are relevant for understanding superconductivity in proximity to itinerant ferromagnetism in multi-valley graphene systems, particularly the ones with full valley and spin polarization. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2507_00158 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Superconductivity via paramagnon and magnon exchange in a 2D near-ferromagnetic full metal and ferromagnetic half-metal Raines, Zachary M Chubukov, Andrey V Superconductivity We study superconductivity in paramagnetic and ferromagnetically-ordered phases in a two-dimensional electron system with parabolic fermionic dispersion and short-range repulsive interaction. In the paramagnetic phase, we find that a weak momentum dependence of a paramagnon propagator parametrically reduces the onset temperature for the pairing compared to that in phenomenological theories which assume a strong dispersion of a paramagnon and also changes the topology of the gap function. In the ferromagnetic phase, we show that the order instantly polarizes low-energy fermionic excitations. We derive the fully renormalized pairing interaction between low-energy fermions, mediated by two transverse Goldstone modes and show that it is attractive in a spatially-odd channel. The pairing temperature in the ferromagnetic phase is found to be a fraction of the Fermi energy, significantly larger than in the paramagnetic phase near the transition. Our results are relevant for understanding superconductivity in proximity to itinerant ferromagnetism in multi-valley graphene systems, particularly the ones with full valley and spin polarization. |
| title | Superconductivity via paramagnon and magnon exchange in a 2D near-ferromagnetic full metal and ferromagnetic half-metal |
| topic | Superconductivity |
| url | https://arxiv.org/abs/2507.00158 |