High-field superconductivity from atomic-scale confinement and spin-orbit coupling at (111)$\mathrm{LaAlO_3/KTaO_3}$ interfaces

TL;DR

This study reveals highly anisotropic, ultra-thin superconductivity at (111) LaAlO3/KTaO3 interfaces, with critical fields exceeding traditional limits due to atomic-scale confinement and spin-orbit effects.

Contribution

It demonstrates unprecedented in-plane critical fields and anisotropic superconductivity at oxide interfaces, highlighting the role of atomic-scale confinement and spin-orbit coupling.

Findings

In-plane critical fields surpass the paramagnetic limit.

Superconducting layer thickness below 1 nm.

Strong anisotropy in critical fields observed.

Abstract

We study the superconducting critical fields of two-dimensional electron systems at (111)$\mathrm{LaAlO_3/KTaO_3}$ interfaces as a function of electrostatic back-gating. Our work reveals inplane critical fields of unprecedented magnitudes at oxide interfaces. By comparing the critical fields in-plane and out-of-plane we discover an extremely anisotropic superconductor with an effective thickness below 1 nm and a 12-fold violation of the Chandrasekhar-Clogston paramagnetic limit. The analysis of magneto-transport indicates that the enhancement of the critical fields is due to an exceptionally thin superconducting layer and to a paramagnetic susceptibility suppressed by spin-orbit scattering.