Superconductivity-driven magnetization modulation in YBa2Cu3O7-{\delta} /SrTiO3/La0.67Sr0.33MnO3 heterostructures

TL;DR

This study reveals a novel long-range proximity effect in heterostructures where superconductivity influences ferromagnet magnetization through an insulator, showing unexpected magnetic modulation at the interface.

Contribution

It demonstrates an unusual magnetic modulation at the FM interface in SC/I/FM heterostructures, indicating Cooper pair tunneling and long-range proximity effects not explained by existing models.

Findings

Magnetization at the FM interface is significantly reduced below Tc.

Cooper pairs tunnel through the insulator and interact with FM magnetization.

The magnetic modulation extends approximately 30 Å from the interface.

Abstract

Using spin polarized neutron reflectivity experiments, we demonstrate an unusual proximity behaviour when the superconductor (SC) and the ferromagnet (FM) are coupled through an insulator (I) in YBa2Cu3O7-{\delta} (SC)/SrTiO3 (I)/La0.67Sr0.33MnO3 (FM) heterostructures. We have observed an unexpected magnetic modulation at the interface region of the FM below the superconducting transition temperature. The magnetization of the FM layer at the I/FM interface was drastically reduced as compared to the magnetization in the rest of the FM layer. This result indicates that the Cooper pairs tunnel across the insulator and interact with the local magnetization at the interface region (extending ~ 30 {\AA}) of the FM causing modification of the magnetization at the interface. This unexpected magnetic behavior cannot be explained on the basis of the existing theoretical models. However, the length scale associated here clearly suggests the long range proximity effect as a result of tunneling of Cooper pairs.