Abstract
Mossbauer transmission spectra taken, at a temperature of 4.2 K, through a thin single-crystal sample gamma -Fe-Mn, in magnetic fields up to 9 T are presented. These spectra have been fitted to the three energetically favoured magnetic spin models of gamma -Mn. The authors' results are not consistent with the (001) model of a collinear antiferromagnet, whereas fits to the (111) and (110) models are good but indistinguishable.