Magnetic ordering in the ternary germanides U 2Co 3Ge 5 and UCo 2Ge 2

Abstract

We have investigated the UCo 2 xGe 2+x, system for −0.2x0.5. The new ternary germanide U 2Co 3Ge 5 orders ferromagnetically below T c = 21 K. UCo 2Ge 2 shows a narrow range of homogeneity on the cobalt-rich side. The stoichiometric germanide orders antiferromagnetically near T N = 160 K. The lattice parameters and the magnetic ordering of the compounds containing an excess of cobalt depend on their thermal treatment. This fact is proposed as an explanation for the ambivalence in the literature concerning the structural and physical properties of this last germanide.