Enhanced Critical Field of Superconductivity at an Oxide Interface.

The nature of superconductivity and its interplay with strong spin-orbit coupling at the KTaO 3 (111) interfaces remain a subject of debate. To address this problem, we grew epitaxial LaMnO 3 /KTaO 3 (111) heterostructures. We show that superconductivity is robust against the in-plane magnetic field, with the critical field of superconductivity reaching ∼25 T in optimally doped heterostructures. The superconducting order parameter is highly sensitive to the carrier density. We argue that spin-orbit coupling drives the formation of anomalous quasiparticles with vanishing magnetic moment, providing significant condensate immunity against magnetic fields beyond the Pauli paramagnetic limit. These results offer design opportunities for superconductors with extreme resilience against the applied magnetic fields.