On the anomalies in some physical properties at the Neel transition of γ-Fe-Mn-Ge alloys

Abstract

Measurements have been made of the electrical resistivity rho , thermal expansivity Delta L/L and elastic modulus E of gamma -Fe-Mn alloys containing 0-8.73 at.%. Ge. Anomalies in rho , Delta L/L and E are observed in the vicinity of the Neel temperature TN for all these alloys. The effect of the Ge content on the anomalous behaviour of Fe-Mn alloy is essentially similar to those of the Al or Si content. The experimental results are qualitatively discussed on the basis of two postulates, i.e. firstly that the valence electron band of Ge overlaps the d band of the matrix so as to induce or enhance the localized moment on the Fe atom sites and secondly that the increase in the Ge content weakens the itinerant electron character of antiferromagnetic gamma -Fe-Mn alloys.