Investigation of ferromagnetism in Mn1−xAl1−yFex+y alloys

The Mn1−xAl1−yFex+yalloys have been magnetically and structurally characterized. X-ray diffraction measurements showed that all investigated specimens possess predominantly a crystallographic phase with B2 structure, besides two minority phases in tiny proportion with structures β-Mn and η (fct, Al-rich). These alloys exhibit no hysteresis nor coercivity. Results of dc magnetization measurements at low temperatures suggest that a ferromagnetic (FM) behavior is ascribed to the main phase with B2 structure, which is in agreement with earlier investigations, although the coexistence of both antiferromagnetic and ferromagnetic exchanges is inferred from the results of low temperature magnetometry and Mössbauer spectroscopy. A remarkable feature observed in the M(T)M(T) curves for these alloys at low temperatures is the abrupt decrease in the total magnetization which occurs with the increase of temperature.