Gd Mossbauer effect and magnetic properties of GdMn6-xCrx Ge6

The compounds GdMn6-xCrxGe6 crystallize in the hexagonal HfFe6Ge6 structure. The magnetic properties of these compounds were determined. The magnetic ordering temperature (Tc =490 K for X=0) and the 3d sublattice magnetization in GdMn6-xCrxGe6 strongly decrease with x. In GdCr6Ge6 the magnetic ordering temperature dropped to Tc =15 K but from the magnetic isotherms studied at lower temperatures it is derived that magnetic ordering is more complex than simple ferromagnetism. there is also appreciable short range ordering above Tc, as was shown by 155Gd Mossbauer spectroscopy.