Evidence for spin-triplet superconducting correlations in metal-oxide heterostructures with non-collinear magnetization

TL;DR

This study provides experimental evidence for spin-triplet superconducting correlations in complex heterostructures with non-collinear magnetization, revealing Josephson effects driven by triplet pairing in ferromagnetic-superconductor interfaces.

Contribution

It demonstrates the existence of spin-triplet superconducting correlations in heterostructures with non-collinear magnetization through experimental measurements.

Findings

Observation of non-collinear magnetic states.

Detection of superconducting currents in mesa-structures.

Josephson effects explained by triplet component penetration.

Abstract

Heterostructures composed of ferromagnetic La0.7Sr0.3MnO3, ferromagnetic SrRuO3, and superconducting YBa2Cu3Ox were studied experimentally. Structures of composition Au/La0.7Sr0.3MnO3/SrRuO3/YBa2Cu3Ox were prepared by pulsed laser deposition, and their high quality was confirmed by X-ray diffraction and reflectometry. A non-collinear magnetic state of the heterostructures was revealed by means of SQUID magnetometry and polarized neutron reflectometry. We have further observed superconducting currents in mesa-structures fabricated by deposition of a second superconducting Nb layer on top of the heterostructure, followed by patterning with photolithography and ion-beam etching. Josephson effects observed in these mesa-structures can be explained by the penetration of a triplet component of the superconducting order parameter into the magnetic layers.