Preparations and photo-physical properties of magnetic semiconductor EuX nanocrystals

磁性半導体EuX(ユーロピウムカルコゲナイド:EuO,EuSなど)ナノ結晶は伝導帯と荷電子帯の間に縮退した4f軌道を有する.この4f軌道から伝導帯への許容遷移は特徴的な光磁気特性を誘起することから,新しい光磁気材料として興味深い.ここでは,この特徴的な磁性半導体EuXナノ結晶の合成および光磁気特性について紹介する.さらに,レーザートラッピング法および自己組織化法を用いたEuXの会合体形成および配列について解説する.EuXナノ結晶は新規な光アイソレーターや光磁気デバイスへの応用が期待される.Magnetic semiconductor, europium chalcogenide nanocrystals (EuX: EuO, EuS and EuSe nanocrystals), are characterized by the narrow 4f orbitals that exist degenerate levels between the conduction band [5d orbitals of Eu(II)] and the valence band (p orbitals of O2-, S2- and Se2-). The 4f-5d electronic transition and spin configuration of europium chalcogenide lead to significant photomagnetic effects, making these nanocrystals promising candidates as active materials in photo-magnetic devices. In this review, the synthesis and characteristic photophysical properties of europium chalcogenide nanocrystals are introduced. Europium chalcogenide nanocrystals, the three-dimensional (3D) aggregates and arrangements of the europium chalcogenide nanocrystals by an optical trapping and self-assemble techniques are demonstrated here. Europium chalcogenide nancrystals have great potential in such applications as novel photo-isolators for optical fibers and photo-magnetic devices