The antiferromagnetic and ferromagnetic properties of Fe2MnSi

The results of extensive magnetization, susceptibility, X-ray and neutron powder diffraction measurements on the stoichiometric intermetallic compound Fe2MnSi are reported. At room temperature the compound is paramagnetic enabling the crystallographic structure to be established as L21 with some degree of preferential DO3 disorder. Between 69 and 214 K the compound is ferromagnetic but below 69 K the manganese atoms become antiferromagnetically ordered whilst the iron atoms remained ferromagnetically aligned. This coincides with a change in the configurational magnetic symmetry to rhombohedral, in which the antiferromagnetically aligned moments are directed along the [111] direction.