Magnetic properties and hyperfine interactions in EuCu2Ge2 single crystals

Abstract

The results of X-ray diffraction, magnetic susceptibility, and Eu-151 Mossbauer spectroscopy studies of single crystals of EuCu2Ge2 grown by a flux method are reported. The magnetic susceptibility and Mossbauer data clearly demonstrate the divalent state of Eu in the temperature range 2-300 K. These data also show that EuCu2Ge2 is an antiferromagnet with two antiferromagnetic transitions at 5.3(1) and 8.2(1) K in contrast to one antiferromagnetic transition at 13-14 K observed for polycrystalline samples. The direction of the Eu magnetic moment at 2.0 K is 49(2)degrees away from the c-axis. The Debye temperature of EuCu2Ge2 determined from the Mossbauer data is 226(2) K. The origin of the differences in magnetic properties of single-crystal and polycrystalline samples of EuCu2Ge2 is discussed in terms of chemical pressure. (C) 2010 Elsevier Ltd. All rights reserved.