3D to 2D Magnetic Ordering of Fe(3+) Oxides Induced by Their Layered Perovskite Structure

[Image: see text] The antiferromagnetic behavior of Fe(3+) oxides of composition RE(1.2)Ba(1.2)Ca(0.6)Fe(3)O(8), RE(2.2)Ba(3.2)Ca(2.6)Fe(8)O(21), and REBa(2)Ca(2)Fe(5)O(13) (RE = Gd, Tb) is highly influenced by the type of oxygen polyhedron around the Fe(3+) cations and their ordering, which is coupled with the layered RE/Ba/Ca arrangement within the perovskite-related structure. Determination of the magnetic structures reveals different magnetic moments associated with Fe(3+) spins in the different oxygen polyhedra (octahedron, tetrahedron, and square pyramid). The structural aspects impact on the strength of the Fe-O-Fe superexchange interactions and, therefore, on the Néel temperature (T(N)) of the compounds. The oxides present an interesting transition from three-dimensional (3D) to two-dimensional (2D) magnetic behavior above T(N). The 2D magnetic interactions are stronger within the FeO6 octahedra layers than in the FeO4 tetrahedra layers.