[10a-M101-1~8] 10.1 新物質・新機能創成（作製・評価技術）

▼ [10a-M101-4] J_eff= 3/2 ferromagnetic insulating state above 1000 K in a double perovskite osmate synthesized by molecular beam epitaxy

〇Yuuki Wakabayashi¹、Yoshiharu Krockenberger¹、Naoto Tsujimoto²、Tommy Boykin¹、Shinji Tsuneyuki²、Yoshitaka Taniyasu¹、Hideki Yamamoto¹ (1.NTT BRL、2.The Univ. of Tokyo)

キーワード：molecular beam epitaxy, double perovskite, ferromagnetic insulator

In magnetic insulating oxides_, the cubic crystal symmetry is thought to be favorable for higher Curie temperatures (T_C), since the network morphology hosting the mechanisms of exchange interactions is subject to the crystal symmetry. Especially for perovskites, it is well known that the crystal symmetry dominates the exchange interactions, e.g., SrRuO₃(pseudo-cubic perovskite, ferromagnetic metal) and CaRuO₃(orthorhombic perovskite, paramagnetic metal). In addition to the symmetry, adopting 5dtransition metal oxides, where spin-orbit coupling (SOC) is enhanced, is a promising way to boost the long range ferri/ferromagnetic (FM) order. For example, it was shown for a pyrochlore osmate (Cd₂Os₂O₇) that the SOC is responsible for its long range order. Here we show that a highly B-site ordered cubic double-perovskite Sr₃OsO₆, which satisfies the above criteria, has the highest T_Cof 1060 K among all insulators and oxides, and the highest magnetic ordering temperature in any compound without 3dtransition elements.