HfFe6Ge6-type YbMn6Ge6-xGax compounds (0.07≤x≤0.72) with large magnetocrystalline anisotropy

The HfFe6Ge6-type YbMn6Ge6-xGa solid solution (0.0less than or equal toxless than or equal to0.72) has been studied by X-ray diffraction, microprobe analysis and powder magnetization measurements. All the compounds order anti ferromagnetically between T-N=481 K for x=0.07 and T-N=349 K for x=0.72 and display more or less pronounced spontaneous magnetization at lower temperature. The corresponding Curie points increase from 40 K for x=0.07 to 319 K for x=0.72. The maximum magnetization values of the Ga-rich compounds (Mapproximate to5 mu(B)/f.u. at 6 K) is compatible with a ferrimagnetic order of the Mn and Yb sublattices whereas the smaller values measured in the Ga-poor compounds suggest the stabilization of non-colinear magnetic structures. All the studied compounds are characterized by rather large coercive fields at low temperature (4.0less than or equal toH(c)less than or equal to8.2 kOe). (C) 2002 Elsevier Science B.V. All rights reserved.