Coexistence of Magnetic Order and Two-dimensional Superconductivity at LaAlO$_3$/SrTiO$_3$ Interfaces

TL;DR

This study reveals that at LaAlO₃/SrTiO₃ interfaces, magnetic order coexists with two-dimensional superconductivity, indicating potential unconventional superconducting phases and complex electronic interactions.

Contribution

It provides direct evidence of magnetic ordering coexisting with superconductivity at the interface, combining transport and magnetic measurements for comprehensive analysis.

Findings

Magnetic order exists from below superconducting transition up to 200 K.

Magnetic moments are oriented in-plane.

Coexistence or phase separation of magnetic and superconducting states is observed.

Abstract

A two dimensional electronic system with novel electronic properties forms at the interface between the insulators LaAlO$_3$ and SrTiO$_3$. Samples fabricated until now have been found to be either magnetic or superconducting, depending on growth conditions. We combine transport measurements with high-resolution magnetic torque magnetometry and report here evidence of magnetic ordering of the two-dimensional electron liquid at the interface. The magnetic ordering exists from well below the superconducting transition to up to 200 K, and is characterized by an in-plane magnetic moment. Our results suggest that there is either phase separation or coexistence between magnetic and superconducting states. The coexistence scenario would point to an unconventional superconducting phase in the ground state.