Mossbauer study of iron ordering, in mixed valence system LuFe2O4

Abstract

Single crystalline LuFe2O4 was grown by the floating zone method. The crystallographic and magnetic properties of the sample were measured using x-ray diffractometer (XRD), Mossbauer 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-C) was determined to be 250 K from the M-T curve and Mossbauer spectra. Just below T-C, the magnetic moment has large value and shows a abrupt change in M-T curve. The Mossbauer spectra have been taken at various temperatures ranging from 4.2 to 370 K. We confirmed that the charge ordering of Fe3+ and Fe2+ ions was begun below 350 K, magnetic superstructure of the different ionic state was formed around 320 K. The isomer shift value of Fe2+ doublet increases with decreasing temperature from 320 to 235 K. At low temperature, Mossbauer spectra consisted of four sextets with magnetic ordering.