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.
@article{arxiv.2111.13278,
title = {Room-temperature ferromagnetism at an oxide/nitride interface},
author = {Qiao Jin and Zhiwen Wang and Qinghua Zhang and Yonghong Yu and Shan Lin and Shengru Chen and Mingqun Qi and He Bai and Qian Li and Le Wang and Xinmao Yin and Chi Sin Tang and Andrew T. S. Wee and Fanqi Meng and Jiali Zhao and Jia-Ou Wang and Haizhong Guo and Chen Ge and Can Wang and Wensheng Yan and Tao Zhu and Lin Gu and Scott A. Chambers and Sujit Das and Gang-Qin Liu and Shanmin Wang and Kui-juan Jin and Hongxin Yang and Er-Jia Guo},
journal= {arXiv preprint arXiv:2111.13278},
year = {2022}
}