Magnetic couplings in MM′X compounds of Cu2Sb type of structure (M,M′=d-metals, X=p-elements as P, As, Sb, …)

Most of the MM′X tetragonal compounds of Cu2Sb type structure, where M,M′ are d-metals and X=P, As, Sb, Ge, etc. exhibit interesting magnetic properties. These compounds have been characterised by magnetisation measurements as well as by neutron diffraction for establishing the magnetic configurations. A first review is made of the different types of magnetic arrangements. Based on the molecular field model for magnetic couplings-thus applying a 2nd order interaction model-the different collinear arrangements derived from experiments are described using the Bertaut's Irreducible Representation Analysis. An exchange matrix based on the Heisenberg type Hamiltonian has been built up on the framework of the Bertaut's Phase Comparison Analysis between the magnetic atoms. Thus, simple arrangements of the magnetic moments have been derived. Long range non-collinear magnetic configurations appear to be highly unlikely, due to very peculiar conditions. This is confirmed experimentally with the many different, but rather simple ferromagnetic, ferrimagnetic and antiferromagnetic configurations that were established.