Investigations of the solid solution NdMn 2− xFe xGe 2 ( x = 0.1−1.4) by magnetic measurements and neutron diffraction

Abstract

The solid solution NdMn 2− x Fe x Ge 2 ( x < 1.4) was studied by means of X-ray powder diffraction, magnetic measurements and neutron diffraction study. A typical SmMn 2Ge 2-like behaviour is observed for x = 0.425. The magnetic structures of NdMn 1.6Fe 0.4Ge 2, NdMn 1.4Fe 0.6Ge 2 and NdMn 1.1Fe 0.9Ge 2 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 NdMn 2− x Fe x Ge 2 and LaMn 2− x Fe x Ge 2 solid solutions are compared, and the effects of Mn substitution on the in-plane magnetic couplings are discussed. The effects of iron substitution on the interplane magnetic couplings are examined. A slight increase of the critical d Mn−Mn distance is observed. In NdMn 1.1Fe 0.9Ge 2, the onset of antiferromagnetism seems to be correlated to a large decrease of the GeGe separation.