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| Auteurs principaux: | , |
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| Format: | Preprint |
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2025
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| Accès en ligne: | https://arxiv.org/abs/2507.00168 |
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| _version_ | 1866916817996349440 |
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| author | Raines, Zachary M Chubukov, Andrey V |
| author_facet | Raines, Zachary M Chubukov, Andrey V |
| contents | We analyze the origin of superconductivity in a ferromagnetically ordered state of multi-layer graphene systems placed in proximity to WSe$_2$. We model these materials by a two-valley system of interacting fermions with small pockets and Ising spin-orbit coupling. The model yields a canted ferromagnetic order, which gives rise to a half-metal. We obtain the magnon spectrum and derive two sets of magnon-mediated 4-fermion interactions: spin-flip interactions mediated by a single magnon and spin-preserving interactions mediated by two magnons. We argue that both processes have to be included on equal footing into the magnon-mediated pairing interaction between low-energy fermions from the filled bands. Then the full magnon-mediated interaction satisfies Adler criterion and for a valley-odd/spatially-even order parameter contains a universal attractive piece. This term is induced by spin-orbit coupling and is confined to energies which are parametrically smaller than the Fermi energy. We argue that, due to retardation, this magnon-mediated attraction gives rise to superconductivity despite that there exists a stronger static repulsion, in close analogy with how phonon-mediated attraction gives rise to pairing in the presence of stronger Coulomb (Hubbard) repulsion. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2507_00168 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Superconductivity induced by spin-orbit coupling in a two-valley ferromagnet Raines, Zachary M Chubukov, Andrey V Superconductivity We analyze the origin of superconductivity in a ferromagnetically ordered state of multi-layer graphene systems placed in proximity to WSe$_2$. We model these materials by a two-valley system of interacting fermions with small pockets and Ising spin-orbit coupling. The model yields a canted ferromagnetic order, which gives rise to a half-metal. We obtain the magnon spectrum and derive two sets of magnon-mediated 4-fermion interactions: spin-flip interactions mediated by a single magnon and spin-preserving interactions mediated by two magnons. We argue that both processes have to be included on equal footing into the magnon-mediated pairing interaction between low-energy fermions from the filled bands. Then the full magnon-mediated interaction satisfies Adler criterion and for a valley-odd/spatially-even order parameter contains a universal attractive piece. This term is induced by spin-orbit coupling and is confined to energies which are parametrically smaller than the Fermi energy. We argue that, due to retardation, this magnon-mediated attraction gives rise to superconductivity despite that there exists a stronger static repulsion, in close analogy with how phonon-mediated attraction gives rise to pairing in the presence of stronger Coulomb (Hubbard) repulsion. |
| title | Superconductivity induced by spin-orbit coupling in a two-valley ferromagnet |
| topic | Superconductivity |
| url | https://arxiv.org/abs/2507.00168 |