Antiferromagnetism of γ-FeMn Alloys

Abstract

The antiferromagnetism of disordered γ‐FeMn alloys has been investigated mainly by neutron diffraction and Mössbauer effect for specimens with different compositions. The average atomic magnetic moment at 0°K decreases, but the Néel temperature increases with increasing Mn concentration. The hyperfine field at 0°K acting on the Fe nucleus, however, remains almost constant. The temperature dependence of the average magnetic moment is also different for different compositions. In contrast with it, the temperature dependence of the hyperfine field is independent of concentration and is markedly different from that of the average magnetic moment. The magnetic moments of iron and manganese have been separately determined by the magnetic diffuse scattering experiments at room temperature. The results indicate that both temperature and composition dependences of the magnetic moments of iron and manganese are quite different in γ‐FeMn alloys.