INVESTIGATIONS OF THE SOLID-SOLUTION NDMN2-XFEXGE2 (X=0.1-1.4) BY MAGNETIC MEASUREMENTS AND NEUTRON-DIFFRACTION

The solid solution NdMn2-xFexGe2 (x < 1.4) was studied by means of X-r ay powder diffraction, magnetic measurements and neutron diffraction s tudy. A typical SmMn2Ge2-like behaviour is observed for x=0.425. The m agnetic structures of NdMn1-6Fe0.4Ge2, NdMn1.4Fe0.6Ge2 and NdMn1.1Fe0. 9Ge2 have been determined between 2 and 300 K. The results lead to the construction of a partial x-T magnetic phase diagram. Results of both NdMn2-xFexGe2 and LaMn2-xFexGe2 solid solutions are compared, and the effects of Mn substitution on the in-plane magnetic couplings are dis cussed. The effects of iron substitution on the interplane magnetic co uplings are examined. A slight increase of the critical d(Mn-Mn) dista nce is observed. In NdMn1.1Fe0.9Ge2, the onset of antiferromagnetism s eems to be correlated to a large decrease of the Ge-Ge separation.