Two-dimensional electron system at the magnetically tunable EuO/SrTiO$_3$ interface

TL;DR

This paper reports a novel method to create a two-dimensional electron system at the EuO/SrTiO3 interface using a controlled redox reaction, enabling magnetic tuning and potential applications in oxide electronics.

Contribution

It introduces a simple, scalable in-situ redox technique to generate 2DESs with tunable magnetic properties at oxide interfaces, expanding functional capabilities.

Findings

Successful creation of 2DES at EuO/SrTiO3 interface.

EuO layer can be tuned from paramagnetic to ferromagnetic.

Method is scalable and generalizable to other oxides.

Abstract

We create a two-dimensional electron system (2DES) at the interface between EuO, a ferromagnetic insulator, and SrTiO3, a transparent non-magnetic insulator considered the bedrock of oxide-based electronics. This is achieved by a controlled in-situ redox reaction between pure metallic Eu deposited at room temperature on the surface of SrTiO3, an innovative bottom-up approach that can be easily generalized to other functional oxides and scaled to applications. Additionally, we find that the resulting EuO capping layer can be tuned from paramagnetic to ferromagnetic, depending on the layer thickness. These results demonstrate that the simple, novel technique of creating 2DESs in oxides by deposition of elementary reducing agents [T. C. R\"odel et al., Adv. Mater. 28, 1976 (2016)] can be extended to simultaneously produce an active, e.g. magnetic, capping layer enabling the realization and control of additional functionalities in such oxide-based 2DESs.