Structural and magnetic investigations of CaBaCo4−xFexO7 solid solutions

Solid solutions of CaBaCo4−xFexO7 (x=0, 0.05, 0.2, 1, 2) were synthesized by glycine-nitrate combustion process. Their structural and magnetic properties were characterized by means of x-ray diffraction and magnetization measurements. In the examined range of the solid solutions, their crystal lattice symmetry changes from orthorhombic with space group Pbn21 (00.5). The magnetic measurements revealed that even small doping (x=0.05) of the transition metal sublattice noticeably suppresses ferrimagnetism of the parent compound and induces an AF transition at 88 K. An increase in the doping concentration lowers the frustration parameter |θCW|/TC from 17.2 (for x=0.05) to 13.7 (for x=2) and strengthens the antiferromagnetic interactions, which manifests itself in the Curie-Weiss temperature (θCW) growth. The samples with x=0.05 and x=0.2 also show an additional magnetic transition at temperatures Tg (55 and 70 K respectively). The temperature irreversibility between the ZFC and FC magnetization curves may suggest the formation of a spin-glass state below that temperature.