A study of Fe2+xMn1-xAl alloys: Structural and magnetic properties

The Fe2+xMn1-xAl alloys were studied experimentally to assess the effect of variations of composition around stoichiometric on the structural and magnetic properties of this system. The results indicate that the ordered L21 (X2YZ) structure of full Heusler alloys can be stabilized with small deviations of composition from the stoichiometric 2:1:1. The saturation magnetization is strongly composition dependent and decreases with the increase of the Mn concentration, in spite of the fact that the Mn atoms carry the largest moment in the ordered phase. The highest Curie temperature was observed for the Fe-richer alloy. Magnetic measurements suggest that atomic disorder and competition of the antiferromagnetic Fe–Mn and Mn–Mn interactions with the ferromagnetic Fe–Fe, Mn–Mn and Fe–Mn interactions lead to a frustrated couplings ending in a reentrant spin-glass behavior at low temperature.