Neutron scattering experiments on the magnetism in Cu-Mn single crystals

We have carried out neutron polarization analysis experiments, and unpolarized neutron scattering experiments, on annealed single crystal Cu-Mn samples of 5, 10, 15 and 25 atomic percent Mn. Peaks in the magnetic diffuse scattering are found at the [1, 1/2 +- delta, 0]-type positions in reciprocal space, where delta = 0.34, 0.29, 0.25 and 0.19 for the 5, 10, 15 and 25 percent Mn samples respectively. This magnetic scattering is symmetry-related to the diffuse nuclear scattering centered at the [1, 1/2, 0]-type positions arising from atomic short range order. The intensity of this diffuse magnetic scattering in all of the alloys decreases smoothly with temperature, approaching zero in the range 300--350 K. The spin-spin correlation range, as judged from the width of the magnetic diffuse peaks, also decreases smoothly with temperature. Neither the width nor the intensity of this magnetic scattering gives any hint of a freezing transition at lower temperature