Cr and Fe Substitution Effects on Magnetic Properties and Phase Stabilities in Tetragonal Mn3(Ga,Ge)

We have investigated Cr and Fe substitution effects on magnetic properties and phase stabilities in D0 22 -type Mn 3 Ga 0.5 Ge 0.5 . The single phase of the D0 22 structure was obtained within the small amount of substitution. The structural parameters in the Cr substitution system show opposite composition dependencies to those in the Fe substitution system. This result implies that the structural properties of the D0 22 structure depend on the number of the valence electron. In contrast to this, the thermal stability of D0 22 phase is influenced by the Fe substitution, whereas the Cr substitution has an insignificant effect on the thermal stability. Magnetization increases with the increasing Cr content but decreases with increasing Fe content. In addition, Mössbauer spectra reveal that the Fe atom occupies at 4d site. Not only the number of the valence electron, but also the site preference of the Cr and Fe atoms plays an important role for the magnetic properties.