Tuning martensitic transformation and magnetoresistance effect by low temperature annealing in Ni45Co5Mn36.6In13.4 alloys

We studied the influence of post-annealing on magnetic and transport properties in Ni45Co5Mn36.6In13.4 alloys. Our results demonstrate that post-annealing at low temperatures, ≤300 deg. C, can lead to a significant change in magnetic properties, martensitic temperature (TM) and magnetoresistance effect through structure relaxations and possible change in atomic order. It was found that TM shifts from 314 to 283 K but the strong metamagnetic behaviour is still retained when the sample is annealed at 300 deg. C for 3 h. Thereupon, a large magnetoresistance effect over an extended temperature range can be achieved through controlling the heat treatment conditions. Meanwhile, the thermal stability of the novel composition is also disclosed through the investigations on low temperature annealing effect.