Model for the Composition-Dependent Ferromagnetic to Antiferromagnetic Transition in Fe2Ti

Abstract

Mössbauer effect and magnetic susceptibility measurements on single‐phase Fe_2+xTi_1−x confirm the finding of Nakamichi that the bulk magnetic properties are very sensitive to deviations from stoichiometry. Well below the Néel temperature antiferromagnetic titanium‐rich material exhibits two narrow‐line ⁵⁷Fe Mössbauer spectra coresponding to the 2a and 6h sites. Ferromagnetic iron‐rich material has additional components and a greatly broadened spectrum. This indicates that Fe₂Ti is basically antiferromagnetic and suggests that the ferromagnetism arises from iron atoms in titanium sites which serve as nuclei for ferromagnetic clusters. These account quantitatively not only for the details of the Mössbauer spectra of iron‐rich material, but also for the saturation magnetization and other features of the susceptibility data.