Room-temperature ferromagnetism at an oxide/nitride interface

TL;DR

This study demonstrates room-temperature ferromagnetism at oxide/nitride interfaces, revealing new magnetic states and interactions in heterostructures of antiferromagnetic chromium compounds, with potential for quantum material applications.

Contribution

It reports the first synthesis and characterization of Cr2O3-CrN superlattices showing ferromagnetism at room temperature, driven by anion-hybridization across interfaces.

Findings

Room-temperature ferromagnetism observed at oxide/nitride interfaces.

Ferromagnetic effect decreases with increasing layer thickness.

First-principles calculations support interfacial Cr3+ spin interactions.

Abstract

Heterointerfaces have led to the discovery of novel electronic and magnetic states because of their strongly entangled electronic degrees of freedom. Single-phase chromium compounds always exhibit antiferromagnetism following the prediction of Goodenough-Kanamori rules. So far, exchange coupling between chromium ions via hetero-anions has not been explored and the associated quantum states is unknown. Here we report the successful epitaxial synthesis and characterizations of chromium oxide (Cr2O3)-chromium nitride (CrN) superlattices. Room-temperature ferromagnetic spin ordering is achieved at the interfaces between these two antiferromagnets, and the magnitude of the effect decays with increasing layer thickness. First-principles calculations indicate that robust ferromagnetic spin interaction between Cr3+ ions via anion-hybridizations across the interface yields the lowest total energy. This work opens the door to fundamental understanding of the unexpected and exceptional properties of oxide-nitride interfaces and provides access to hidden phases at low-dimensional quantum heterostructures.