Strong violation of the Pauli limit for the upper critical field of the KTaO₃(111) interfaces

The nature of superconductivity and its interplay with strong spin–orbit coupling at the KTaO₃(111) interfaces remain a subject of debate. I will talk about our recent experiments on epitaxial growth and superconductivity of KTaO₃(111) heterostructures. Our results 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 and orientation of the magnetic field. The strong violation of Pauli limit for the upper critical field of the KTaO₃(111) interfaces is due to spin–orbit coupling which motivates the formation of anomalous quasiparticles with vanishing magnetic moment. These results offer design opportunities for superconductors with extreme resilience against the applied magnetic fields.