Magnetic properties and structures of some ordered (FeMn) 3 Si alloys

Magnetic and crystallographic properties of the (FeMn) 3 Si system have been studied by X-ray and neutron diffraction magnetization resistivity and magnetoresistivity measurements. The single-phase alloys have been found to crystallize in the L2 1 A structure and to have ferromagnetic properties at low Mn concentrations. At higher concentrations the alloys exhibit a more complex behaviour, having antiferromagnetic components below a temperature T R which is almost concentration independent. The resistivity showed anomalies at T R as well as at the Curie point. The variation of the magnetic moment on each site has been determined as a function of concentration and is discussed in terms of environmental changes occurring as a result of Mn additions.