Ferromagnetism above 1000 K in a highly cation-ordered double-perovskite insulator Sr3OsO6

Yuki K Wakabayashi; Yoshiharu Krockenberger; Naoto Tsujimoto; Tommy Boykin; Shinji Tsuneyuki; Yoshitaka Taniyasu; Hideki Yamamoto

doi:10.1038/s41467-019-08440-6

Ferromagnetism above 1000 K in a highly cation-ordered double-perovskite insulator Sr₃OsO₆

Nat Commun. 2019 Feb 12;10(1):535. doi: 10.1038/s41467-019-08440-6.

Authors

Yuki K Wakabayashi¹, Yoshiharu Krockenberger², Naoto Tsujimoto³, Tommy Boykin², Shinji Tsuneyuki³, Yoshitaka Taniyasu², Hideki Yamamoto²

Affiliations

¹ NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato Wakamiya, Atsugi, Kanagawa, 243-0198, Japan. yuuki.wakabayashi.we@hco.ntt.co.jp.
² NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato Wakamiya, Atsugi, Kanagawa, 243-0198, Japan.
³ Department of Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.

Abstract

Magnetic insulators have wide-ranging applications, including microwave devices, permanent magnets and future spintronic devices. However, the record Curie temperature (T_C), which determines the temperature range in which any ferri/ferromagnetic system remains stable, has stood still for over eight decades. Here we report that a highly B-site ordered cubic double-perovskite insulator, Sr₃OsO₆, has the highest T_C (of ~1060 K) among all insulators and oxides; also, this is the highest magnetic ordering temperature in any compound without 3d transition elements. The cubic B-site ordering is confirmed by atomic-resolution scanning transmission electron microscopy. The electronic structure calculations elucidate a ferromagnetic insulating state with J_eff = 3/2 driven by the large spin-orbit coupling of Os⁶⁺ 5d² orbitals. Moreover, the Sr₃OsO₆ films are epitaxially grown on SrTiO₃ substrates, suggesting that they are compatible with device fabrication processes and thus promising for spintronic applications.