Magnetization, Lattice Constants and Hydrostatic Pressure Effect on the Curie Temperature of (Co1-xMnx)2B

Measurements of the magnetization, lattice constants and hydrostatic pressure effect on the Curie temperature T c were carried out on the compounds (Co 1- x Mn x ) 2 B, 0 ≦ x ≦1. The compounds were ferromagnetic when \(x 0.6\) and paramagnetic when \(0.6 x 1\). The magnetization at 4.2 K and T c were analysed on the basis of the pair interaction model and the local environment effect, on the assumption that the central Co atom loses the moment or the moment of Mn is antiparallel to the neighboring Mn atoms, when the numbers of neighbor Mn atoms are more than seven. The composition dependence of lattice constants a and c did not follow the Vegard's law, and was explained by the magnetic contribution. The data on the pressure effect on T c shows relatively large contribution of the Mn-Mn pair to the exchange interaction.