Magnetic Studies of the Metallic Perovskite-Type Compounds of Manganese

In this study of metallic perovskites Mn 3 MX (M=metal, X=C, N) we emphasize the influence of the (outer) electron concentration on the sequences of crystallographic transitions, on the magnetic ordering temperatures and on the constant (Pauli-type like) part of the magnetic susceptibility. A great variety of observed magnetic structures and transitions (including spin rotations) are described for carbides and nitrides. The Labbe-Jardin tight binding model which invokes a p-d II hybridization between N and Mn orbitals having their energy levels near to the Fermi surface provides the possibility of great variations of the density of states versus temperature and is in qualitative agreement with experiment. It also explains that small substitutions on X have a more drastical effect than those can M.