Effect of annealing on the martensitic transformation and magnetoresistance in Ni–Mn–Sn ribbons

Ni 44.1 Mn 44.2 Sn 11.7 ribbons were prepared by melt spinning. After heat treatment, the martensitic transformation (MT) temperature increases obviously in the annealed ribbons. Large magnetoresistance (MR) was observed in these ribbons. Under the field of 50 kOe, the maximum values of negative MR were 22% for melt-spun ribbons at 240 K and 38% for annealed ribbons at 268 K, respectively. The annealing effect on MT and MR, together with the origin of the large MR, has been discussed in this paper.