High magnetic field study of the anisotropy and neutron diffraction investigation of the crystal and magnetic structure of YCo4.5Ge0.5

The solubility limit of Ge in the YCo5-xGex structure is shown to be close to one Ge atom per formula unit by combining diffraction techniques and electron microscopy. The evolution of the crystal structure of the YCo4.Ge-5(0.5) compound is studied by X-ray and neutron diffraction experiments. A preferential substitution scheme is observed, the Ge atom being preferentially located on the Co 3g positions. Powder neutron diffraction results shows that the Co magnetic moments are significantly reduced by the presence of Ge in the crystal structure. The intrinsic magnetic properties such as the saturation magnetization and the magnetocrystalline anisotropy parameters are determined at 4.2 and 300 K from a fit of the isothermal magnetization curves measured in applied field up to 23T. Ge for Co substitution induces a reduction of the first order anisotropy parameter. The large magnetocrystalline anisotropy found for YCo45Ge0.5 is not much reduced upon heating from 4 to 300 K. The results are compared and commented in the light of that reported earlier for YCo5 and other homologues such as YCo4Al or YCo4Ga. (C) 2010 Elsevier B.V. All rights reserved.