Intrinsic spin-orbit coupling in superconducting {\delta}-doped SrTiO3 heterostructures

TL;DR

This paper demonstrates intrinsic spin-orbit coupling in ultrathin SrTiO3 heterostructures, leading to a significant violation of the Pauli limit in 2D superconductors, revealing a new regime of non-perturbative spin-orbit effects.

Contribution

It reports the first observation of intrinsic spin-orbit coupling effects in superconducting SrTiO3 heterostructures with ultrathin doping layers.

Findings

Superconducting SrTiO3 heterostructures exceed the Pauli limit by a factor of 4.

Transport scattering times are several orders of magnitude higher than in conventional superconductors.

Spin-orbit coupling effects are non-perturbative in this regime.

Abstract

We report the violation of the Pauli limit due to intrinsic spin-orbit coupling in SrTiO3 heterostructures. Via selective doping down to a few nanometers, a two-dimensional superconductor is formed, geometrically suppressing orbital pair-breaking. The spin-orbit scattering is exposed by the robust in-plane superconducting upper critical field, exceeding the Pauli limit by a factor of 4. Transport scattering times several orders of magnitude higher than for conventional thin film superconductors enables a new regime to be entered, where spin-orbit coupling effects arise non-perturbatively.