Large Magnetoelectric Response in Sr2IrO4/SrTiO3 superlattices with non-equivalent interfaces

TL;DR

This study demonstrates a significant magnetoelectric response in Sr2IrO4/SrTiO3 superlattices achieved through engineered non-equivalent interfaces, revealing a new pathway for integrating strong magnetoelectric effects into thin-film devices.

Contribution

The paper introduces a novel design of superlattices with non-equivalent interfaces that enhances magnetoelectric coupling via interfacial electron occupation and spin-orbit interactions.

Findings

Maximum magnetoelectric coefficient of ~980 mV cm-1 Oe-1 measured.

Lopsided electron occupation at Ti interfacial ions confirmed by spectroscopy.

Strong coupling between antiferromagnetism and asymmetric electron occupation demonstrated.

Abstract

Large magnetoelectric response in thin films is highly desired for high-throughput and high-density microelectronic applications. However, the d0 rule in single-phase compounds usually results in a weak interaction between ferroelectric and magnetic orders; the magnetoelectric coupling via elastic resonance in composites restricts their thin-film integration in broadband. Here, we effectuate a concurrence of ferroelectric-like and antiferromagnetic phase transitions in Sr2IrO4/SrTiO3 superlattices by artificial design periodically non-equivalent interfaces, where a maximum magnetoelectric coefficient of ~980 mV cm-1 Oe-1 can be measured. Evidenced by synchrotron X-ray absorption and electron energy loss spectroscopies, a lopsided electron occupation occurs at the interfacial Ti ions. From perturbative calculations and numerical results, a strong coupling of antiferromagnetism and asymmetric electron occupation mediated by spin-orbit interaction leads to a large bulk magnetoelectric response. This atomic tailoring of the quantum order parameters in 3d and 5d oxides provides an alternative pathway towards strong magnetoelectric effects with thin-film integrations.