Neutron diffraction measurements were made on polycrystalline samples of a 75% Pd—25% Mn alloy. It was found that long-range positional order could be obtained by appropriate heat treatment and that this order was of the one-dimensional antiphase domain type with a period of 4 cubic unit cells. Below 170°K antiferromagnetic reflections were observed for this ordered alloy. A magnetic structure is proposed which satisfactorily accounts for the observed magnetic reflection intensities. On the basis of this structure the atomic magnetic moments are $(4.0\mathrm{}\pm 0.2){\mu }_B/\mathrm{Mn}$ and $(0.2\mathrm{}\pm 0.1){\mu }_B/\mathrm{Pd}$.

• Received 16 July 1962

DOI:https://doi.org/10.1103/PhysRev.128.2118