Emerging magnetism and anomalous Hall effect in iridate-manganite heterostructures.

John Nichols,Daniel Haskel,Tricia L Meyer,Gyula Eres,Andreas Herklotz,Jonathan R Petrie,Shinbuhm Lee,John W Freeland,Jian Liu,Thomas Z Ward,Dongkyu Lee,Di Yi,Xiang Gao,Valeria Lauter,Er-Jia Guo,Michael R Fitzsimmons,Ho Nyung Lee

doi:10.1038/ncomms12721

Abstract

Strong Coulomb repulsion and spin–orbit coupling are known to give rise to exotic physical phenomena in transition metal oxides. Initial attempts to investigate systems, where both of these fundamental interactions are comparably strong, such as 3d and 5d complex oxide superlattices, have revealed properties that only slightly differ from the bulk ones of the constituent materials. Here we observe that the interfacial coupling between the 3d antiferromagnetic insulator SrMnO3 and the 5d paramagnetic metal SrIrO3 is enormously strong, yielding an anomalous Hall response as the result of charge transfer driven interfacial ferromagnetism. These findings show that low dimensional spin–orbit entangled 3d–5d interfaces provide an avenue to uncover technologically relevant physical phenomena unattainable in bulk materials.

Highlights

Strong Coulomb repulsion and spin–orbit coupling are known to give rise to exotic physical phenomena in transition metal oxides
Even though there are a few examples of successful synthesis of 3d–5d superlattices[14,15,16,17], there are no examples of strong interfacial coupling between these materials as the field remains in its infancy
Since the dominant magnetic ion is Mn and the anomalous Hall effect (AHE) is driven by magnetism, it is logical to assume the majority of AHE resides within the SMO layers

Summary

Introduction

Strong Coulomb repulsion and spin–orbit coupling are known to give rise to exotic physical phenomena in transition metal oxides. We observe that the interfacial coupling between the 3d antiferromagnetic insulator SrMnO3 and the 5d paramagnetic metal SrIrO3 is enormously strong, yielding an anomalous Hall response as the result of charge transfer driven interfacial ferromagnetism These findings show that low dimensional spin–orbit entangled 3d–5d interfaces provide an avenue to uncover technologically relevant physical phenomena unattainable in bulk materials. With the emergence of a novel insulating ground state with effective total angular momentum Jeff 1⁄4 1/2 that is induced by strong spin–orbit coupling (SOC), there has been enormous interest in many Ir-based 5d TMOs18–21, which have a SOC interaction strength (x) with an energy scale comparable to the on-site Coulomb interaction (U)[22] This interest is largely due to theoretical predictions of exotic physical properties such as unconventional superconductivity[23], Weyl semi-metals[20] and topological insulators[24,25] in 5d systems. As the emergence of ferromagnetism and the AHE are completely absent from either parent compound, this discovery provides the first experimental evidence of strong coupling at the interface of 3d and 5d materials

Methods

Results

Conclusion