Mössbauer study of iron ordering in mixed valence system LuFe₂O₄

다국어 초록 (Multilingual Abstract)

<P>Single crystalline LuFe<SUB>2</SUB>O<SUB>4</SUB> was grown by the floating zone method. The crystallographic and magnetic properties of the sample were measured using x-ray diffractometer (XRD), Mössbauer spectroscopy, and vibrating sample magnetometer (VSM). The crystal structure was found to be a two-dimensional layered-type rhombohedral with space group R3-mh. The magnetic Curie temperature (T<SUB>C</SUB>) was determined to be 250 K from the M -T curve and Mössbauer spectra. Just below T<SUB>C</SUB>, the magnetic moment has large value and shows a abrupt change in M -T curve. The Mössbauer spectra have been taken at various temperatures ranging from 4.2 to 370 K. We confirmed that the charge ordering of Fe<SUP>3+</SUP> and Fe<SUP>2+ </SUP>ions was begun below 350 K, magnetic superstructure of the different ionic state was formed around 320 K. The isomer shift value of Fe<SUP>2+</SUP> doublet increases with decreasing temperature from 320 to 235 K. At low temperature, Mössbauer spectra consisted of four sextets with magnetic ordering. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)</P>