Effects that can stabilise multiple spin-density waves

Abstract

Antiferromagnetism on the face-centred cubic lattice is frustrated. The different competing spin arrangements are degenerate in the classical limit of the Heisenberg model. The author considers quantum-mechanical spin fluctuations, using the Holstein-Primakoff transformation, as a perturbation to lift this degeneracy and find that the collinear spin arrangement is stabilised. When he considers the inclusion of paramagnetic impurities, however, he finds that non-collinear arrangements are locally preferred. He suggests this scenario as a possible explanation for the fact that manganese, when quenched in a face-centred cubic lattice, can be driven from a collinear to non-collinear spin arrangement by doping with either nickel, iron or iridium.