Kinetic arrest behavior in martensitic transformation of NiCoMnSn metamagnetic shape memory alloy

High-field magnetic measurements were carried out in order to investigate behaviors of field-induced reverse martensitic transformation and kinetic arrest of NiCoMnSn metamagnetic shape memory alloy. In the thermomagnetization curves, it was confirmed that the reverse martensitic transformation temperature decreases 67 K by applying magnetic field of 5 T, while in the magnetic field cooling process under 5 T, martensitic transformation does not occur down to low temperatures. Equilibrium magnetic field, defined from the critical magnetic fields of the metamagnetic evidence in the magnetization curves, exhibits almost constant below about 100 K, suggesting that the entropy change becomes zero, which is considered to cause kinetic arrest behavior.

Research highlights▶ NiMnZ (Z = Ga, Al, In, Sn, Sb) Heusler alloys are now very attractive because of their unique physical properties, such as, magnetic shape memory effect, magnetic field-induced phase transition, inverse magnetocaloric effect, magnetoresistance effect and the giant magnetothermal conductivity. ▶ In our previous investigations for the NiCoMnSn alloy, the behavior of the shape recovery due to the magnetic field induced reverse transformation has been reported. However, the detailed investigations on the magnetic properties such as metamagnetic behavior have not been made. ▶ In our present manuscript, we show the experimental results of the magnetic properties under the magnetic fields up to 12 T for NiCoMnSn alloy. We demonstrated the kinetic arresting behavior of the martensitic transformation under the high magnetic fields and thermodynamically discussed it. In addition, we analyzed the structure of the martensitic phase with a long period stacking structure and showed a lattice change between the before and the after the martensitic transformation. We believe that these results are high importance for understanding the interesting physical properties of the Ni-based ferromagnetic shape memory alloys and its applications.