Structural and magnetic properties of the half-ferromagnetic Co2+x+yMn1-xAl1-y alloys

Abstract

Co 2+x+y Mn 1−x Al 1−y intermetallic compounds have been prepared by arc melting and studied with X-ray diffraction and magnetization measurements to ascertain the effect of deviations of composition from the stoichiometry on the ferromagnetism of this system. Hysteresis loops registered at room temperature show a soft ferromagnetic behavior in excess Co. In off-stoichiometric alloys the saturation magnetization is lower than in Co 2 MnAl, whereas the Curie temperature T C is higher in all the studied alloys. T C varies substantially with variations in composition and increases with the Mn content. In the source of this behavior a volume effect is inferred which is expected to lead to strengthened ferromagnetic exchanges.

Strong dependence of ferrimagnetic properties on Co concentration in the Mn1−xAl1−yCox+y system

“…The ternary system MneAleCo has a variety of interesting magnetic phases where some regions still remain practically unexplored, despite some phases have been intensively studied, as for instance, the Co 2 MnAl Heusler alloys [1]. In the MneAl system a metastable ferromagnetic phase was reported in the 1960s [2], which has a body-centered tetragonal structure at 45 at.…”

A Mössbauer effect study of the Fe2+x Mn1–x Al Heusler alloys

“…The large majority of Heusler alloys order ferromagnetically and saturate in applied magnetic fields of less then 5 kOe at low temperatures [7][8][9][10][11][12][13][14][15][16]. Some indeed do order antiferromagnetically, particularly those compounds containing a group 3B element in which the magnetic moment is confined to the Y sites, usually occupied by Mn.…”