${\mathrm{Fe}}_{1-x}{\mathrm{Al}}_x$ exhibits interesting magnetic and anomalous structural properties as a function of composition and sample processing conditions arising from thermal or off-stoichiometric chemical disorder, and, although well studied, these properties are not understood. In stoichiometric B2 FeAl, including the effects of partial long-range order, i.e., thermal antisites, we find the experimentally observed paramagnetic response with nonzero local moments, in contrast to past investigations that find either a ferromagnetic or nonmagnetic state, both inconsistent with experiment. Moreover, from this magnetochemical coupling, we are able to determine the origins of the observed lattice constant anomalies found in ${\mathrm{Fe}}_{1-x}{\mathrm{Al}}_x$ for $x\simeq 0.25–0.5$ under various processing conditions.

• Received 29 January 2004

DOI:https://doi.org/10.1103/PhysRevB.71.064408