Mulders A M, Lawrence S M, Staub U, Garcia-Fernandez M, Scagnoli V, Mazzoli C, Pomjakushina E, Conder K, Wang Y
Department of Imaging and Applied Physics, Curtin University of Technology, Perth, WA 6845, Australia.
Phys Rev Lett. 2009 Aug 14;103(7):077602. doi: 10.1103/PhysRevLett.103.077602. Epub 2009 Aug 12.
Geometrical frustration of the Fe ions in LuFe2O4 leads to intricate charge and magnetic order and a strong magnetoelectric coupling. Using resonant x-ray diffraction at the Fe K edge, the anomalous scattering factors of both Fe sites are deduced from the (h/3 k/3 l/2) reflections. The chemical shift between the two types of Fe ions equals 4.0(1) eV corresponding to full charge separation into Fe2+ and Fe3+. The polarization and azimuthal angle dependence of the superlattice reflections demonstrate the absence of differences in anisotropic scattering revealing random orientations of the Fe2+ orbitals characteristic of an orbital glass state.
LuFe₂O₄中Fe离子的几何阻挫导致了复杂的电荷和磁序以及强磁电耦合。利用Fe K边的共振X射线衍射，从（h/3 k/3 l/2）反射中推导出两个Fe位点的反常散射因子。两种Fe离子之间的化学位移为4.0(1) eV，对应于完全电荷分离为Fe²⁺和Fe³⁺。超晶格反射的极化和方位角依赖性表明，各向异性散射不存在差异，揭示了轨道玻璃态特征的Fe²⁺轨道的随机取向。
