Oscillatory Non-collinear Magnetism Induced by Interfacial Charge Transfer in Metallic Oxide Superlattices

TL;DR

This study discovers a novel oscillatory non-collinear magnetic structure in oxide superlattices caused by interfacial charge transfer and complex spin interactions, opening new avenues for spintronic device engineering.

Contribution

It reveals a new non-collinear magnetic state in oxide superlattices driven by interfacial charge transfer and a helical spin model, differing from conventional multilayer interactions.

Findings

Oscillatory magnetic angle varies with LNO thickness.

Magnetic behavior inconsistent with bilinear and biquadratic models.

A helical spin model explains the observed non-collinear structure.

Abstract

Interfaces between correlated complex oxides are promising avenues to realize new forms of magnetism that arise as a result of charge transfer, proximity effects and locally broken symmetries. We report upon the discovery of a non-collinear magnetic structure in superlattices of the ferromagnetic metallic oxide La2/3Sr1/3MnO3 (LSMO) and the correlated metal LaNiO3 (LNO). The exchange interaction between LSMO layers is mediated by the intervening LNO, such that the angle between the magnetization of neighboring LSMO layers varies in an oscillatory manner with the thickness of the LNO layer. The magnetic field, temperature, and spacer thickness dependence of the non-collinear structure are inconsistent with the bilinear and biquadratic interactions that are used to model the magnetic structure in conventional metallic multilayers. A model that couples the LSMO layers to a helical spin state within the LNO fits the observed behavior. We propose that the spin-helix results from the interaction between a spatially varying spin susceptibility within the LNO and interfacial charge transfer that creates localized Ni2+ states. This provides a new approach to engineering non-collinear spin textures in metallic oxide heterostructures that can be exploited in devices based on both spin and charge transport.