Ferromagnetic superconductivity with excitonic Cooper pairs: Application to Γ-valley twisted semiconductors
2026-05-20
We present a theory of ferromagnetic superconductivity that emerges upon doping a correlated ferromagnetic insulator through the condensation of excitonic Cooper pairs, which are charge-2 e bosonic quasiparticles made of Cooper pairs strongly hybridized with excitons. Using a strong-coupling expansion supported by exact diagonalization, we analyze a model of spin-polarized electrons and show that excitonic Cooper pairs form from electron-hole fluctuations upon doping a strongly correlated insulator. We characterize their binding energy, effective mass, and the resulting superconducting transition temperature. We propose possible realization of spin-polarized superconductivity in twisted semiconductors with honeycomb moiré superlattice.