Neutron study of the magnetic-moment distribution in Co-Mn alloys

Magnetization and polarized-neutron diffuse-scattering measurements were made on Co-Mn alloys to determine the effects of local environment on their magnetic-moment distributions. Results show that the average ferromagnetic moment of Mn is small ($\sim 0.3{\mu }_B$) and antiparallel to the Co moments, which are large but decrease rapidly with increasing Mn content. Local environment effects are mainly confined to the Co moments with no indication of spatially correlated Mn moment fluctuations. It is concluded that the small Mn moment, relative to that usually observed for Mn in fcc alloys, is not due to a static distribution of parallel and antiparallel Mn moments. A dynamic fluctuation, as suggested by Jo and Miwa, may account for this low Mn moment.