Observation of transient superconductivity at the LaAlO$_3$/SrTiO$_3$ interface

TL;DR

This study reports a transient superconducting state at the LaAlO₃/SrTiO₃ interface, induced by magnetic fields and dependent on charge density, revealing complex interplay between superconductivity and ferromagnetism.

Contribution

It provides the first observation of a metastable, transient superconducting phase influenced by magnetic fields and charge density at oxide interfaces.

Findings

Superconductivity appears transiently under magnetic field assistance.

The metastable state depends critically on charge carrier density.

Superconductivity coexists with ferromagnetism, influenced by a Lifshitz transition.

Abstract

We report the observation of a magnetic field assisted transient superconducting state in the two dimensional electron gas existing at the interface of LaAlO$_3$/SrTiO$_3$ heterostructures. This metastable state depends critically on the density of charge carriers in the system. It appears concomitantly with a Lifshitz transition as a consequence of the interplay between ferromagnetism and superconductivity and the finite relaxation time of the in-plane magnetization. Our results clearly demonstrate the inherently metastable nature of the superconducting state competing with a magnetic order in these systems. The co-existence of superconductivity and ferromagnetism in the conducting electronic layer formed at the interface of insulating oxides has thrown up several intriguing and as yet unanswered questions. An open question in this field is the energetics of the interplay between these two competing orders and the present observation goes a long way in understanding the underlying mechanism.