SUSCEPTIBILITY OF (GD,LA)MN-2(GE,SI)(2) COMPOUNDS IN THE MAGNETICALLYORDERED REGIME

The susceptibility of ThCr2Ge2-type compounds with the composition (Gd ,La)Mn-2(Ge,Si)(2) has been investigated experimentally at temperature s at which the Mn-sublattice is still magnetically ordered, and explai ned in terms of a simple model. The temperature behaviour of the susce ptibility can be explained as a result of the interplay between the te mperature dependent antiferromagnetic Mn-Mn interaction and the net R- Mn interaction acting on the Mn-sublattice due to polarisation of the (paramagnetic) R-sublattice. There is good agreement between model cal culations and experiment, enabling the determination of reliable estim ates for the Mn-Mn and R-Mn interaction.