Magnetic Properties of Fe₆₅(Ni_1-<i>x</i>Mn_<i>x</i>)₃₅ Ternary Alloys

Abstract

Magnetic properties of Fe 65 (Ni 1- x Mn x ) 35 ternary alloys which have the f.c.c. structure over the whole range of x were investigated. It was found that the alloys are antiferromagnetic in the composition range of 1≥ x >0.3 and are ferromagnetic in the composition range of 0≤ x <0.3. In the ferromagnetic region, the Curie temperature and the spontaneous magnetization decrease rapidly with increasing x or with the decrease of mean electron concentration. Many physical properties of the alloys are discussed on the basis of three postulates, i.e. , 1) electrons at Mn sites have itinerant character, 2) electrons at Ni sites have localized character and 3) at Fe sites, electrons have itinerant character in the antiferromagnetic range and localized character in the ferromagnetic range. The relation between the atomic distance and the magnetic moment is discussed. The origin of the Invar effect is qualitatively explained on these bases.