Direct observation of charge order and an orbital glass state in multiferroic LuFe2O4.
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.
Department of Imaging and Applied Physics, Curtin University of Technology, Perth, WA 6845, Australia.
A M
AM
Mulders
S M
SM
Lawrence
U
U
Staub
M
M
Garcia-Fernandez
V
V
Scagnoli
C
C
Mazzoli
E
E
Pomjakushina
K
K
Conder
Y
Y
Wang