© 2010 American Institute of Physics

Published in Applied Physics Letters, Vol. 97 No. 6 (2010) at doi: 10.1063/1.3467460


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.