The phase evolution, magnetic and exchange bias properties in Fe50Mn24+xGa26−x (x = 0–3) melt-spun ribbons

Effect of Ga content on the phase constitution, magnetic phase transition temperatures (TC), and exchange bias (EB) behaviors of Fe50Mn24+xGa26−x (x = 0, 0.5, 1, 3) as-spun ribbons have been investigated. Fe50Mn24Ga26 ribbon exhibits a magnetic phase transition of B2-type structure from FM to PM state at TC1 = 190 K. Another magnetic phase transition of face-center-cubic structure from AFM to FM takes place at TC2 = 240 K for Fe50Mn25Ga25 sample. The values of exchange bias field (HE) at 10 K after field-cooling (FC) at 30 kOe from 300 K are 14, 41, 1886, 1740 Oe, respectively, as x is increased from 0 to 3. The phenomena are attributed to the change of exchange interactions at FM/AFM interfaces due to the change of proportion of FM and AFM phases in low temperature magnetic states. The maximum exchange bias field HE = 2.4 kOe at 10 K after field-cooling at 40 kOe is observed for Fe50Mn25Ga25.

► Melt spun Fe50Mn24+xGa26−x (x = 0, 0.5, 1, 3) ribbons were prepared.
► Their crystal structure, microstructure, magnetic phase transition and EB behavior are studied.
► The correlation between exchange bias effect and microstructure is discussed.
► The giant exchange bias field of 2.4 kOe is observed in Fe50Mn25Ga25 ribbon with face-center-cubic structure.