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Superconductivity mediated by Rashba-like coupling to polar modes
Motivated by experimental evidence suggesting a connection between superconductivity and ferroelectricity in bulk SrTiO3 and KTaO3-based heterostructures, we study a pairing mechanism based on spin-orbit assisted coupling between the conduction electrons and the soft ferroelectric modes. We use ab initio computations supplemented with a microscopic model to show robust Rashba-like coupling and BCS pairing constant. The ab initio computations enable us to go beyond the linear-in-momentum conventional Rashba-like interaction and naturally explain a dome behaviour. The dome is attributed to a momentum dependent quenching of the angular momentum due to a competition between spin-orbit and hopping energies. These results make the Rashba dynamic coupling to the ferroelectric soft mode a compelling pairing mechanism in doped polar metals.