Growth of layered Lu2Fe3O7 and Lu3Fe4O10 single crystals exhibiting long-range charge order via the optical floating-zone method

We report the controlled growth of single crystals of intercalated layered Lu1+n Fe2+nO4+3n-delta(n = 1,2) with different oxygen stoichiometries delta. For the first time crystals sufficiently stoichiometric to exhibit superstructure reflections in X-ray diffraction attributable to charge ordering were obtained. The estimated correlation lengths tend to be smaller than for not intercalated LuFe2O4. For Lu2Fe3O7, two different superstructures were observed, one an incommensurate zigzag pattern similar to previous observations by electron diffraction, the other an apparently commensurate pattern with (1/31/30) propagation. Implications for the possible charge order in the bilayers are discussed. Magnetization measurements suggest reduced magnetic correlations and the absence of an antiferromagnetic phase.