Solid-phase rare earth monoxides have been recently synthesized via thin film epitaxy. However, it has been difficult to synthesize heavy rare earth monoxides owing to their severe chemical instability. In this study, rocksalt-type heavy rare earth monoxides REOs (RE = Tb, Dy, Er) were synthesized for the first time, as single-phase epitaxial thin films. The REOs were characterized by hard X-ray photoemission spectroscopy, X-ray absorption spectroscopy, resonant photoemission spectroscopy, and magnetization measurements. These REOs showed metallic electronic states with the almost localized 4f states, indicating the 4fⁿ5d¹ electronic configurations of Tb, Dy, and Er ions. X-ray magnetic circular dichroism measurements of TbO evidenced the magnetic ordering of the 4f spins below the Curie temperature (T_C). The T_C was evaluated to be 233 K for TbO, 142 K for DyO, and 88 K for ErO, where the T_C decreased with the 4f electron number, approximately proportional to the de Gennes factor.

中文翻译：

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岩盐型重稀土一氧化碳 TbO、DyO 和 ErO，表现出金属电子态和铁磁性


最近通过薄膜外延合成了固相稀土一氧化物。然而，由于其严重的化学不稳定性，合成重稀土一氧化氢一直很困难。在这项研究中，首次合成了岩盐型重稀土一氧化碳 REO （RE = Tb， Dy， Er） 作为单相外延薄膜。通过硬 X 射线光电子工光谱、X 射线吸收光谱、共振光电子工光谱和磁化测量对 REO 进行表征。这些 REO 显示出金属电子态，具有几乎局域化的 4f 态，表明 Tb、Dy 和 Er 离子的 4fⁿ5d¹ 电子构型。TbO 的 X 射线磁性圆二色性测量证明了居里温度 （TC） 以下 4f 自旋的磁排序。评估 TbO 的 T_C 为 233 K，DyO 为 142 K，ErO 为 88 K，其中 TC 随 4f 电子数的增加而降低，与 de Gennes 因子大致成正比。