Significantly large inverse magnetic entropy changes (ΔSM) and magnetoresistance (MR) were observed at the inverse martensitic phase transitions of the Ga-based magnetic shape memory Heusler alloys: Ni50−xCoxMn32−yFeyGa18. The crystal structures of alloys were tetragonal at 300 K and the phase transition temperatures and magnetic properties were found to be correlated with the degree of tetragonal distortion. The maximum peak values of the ΔSM and MR at H = 5 T were determined as ≈ (+)31 J Kg−1 K−1 and ≈−21%, respectively, for x = 8 and y = 2. The relatively small hysteretic loss and large refrigeration capacity observed in this system make these compounds promising materials for applications.
Pathak, Arjun K., Dubenko, Igor, Karaca, Haluk E., Stadler, Shane and Ali, Naushad. "Large Inverse Magnetic Entropy Changes and Magnetoresistance in the Vicinity of a Field-Induced Martensitic Transformation in Ni50−xCoxMn32−yFeyGa18." (Aug 2010).