Realization of magnetic field-induced reversible martensitic transformation in NiCoMnGa alloys

Effect of a magnetic field on martensitic transformation in the NiCoMnGa alloys was investigated. A field-induced reversible martensitic transformation from the martensitic phase of low magnetization to the parent phase of high magnetization has been realized. The substitution of Co for Ni atoms has turned the magnetic ordering of the parent phase from partially antiferromagnetic to ferromagnetic, resulting in a large magnetization change across the transformation, which dramatically enhances the magnetic field driving force. The transformation temperature can be downshifted by magnetic field at a rate up to 14K∕T in Ni37Co13Mn32Ga18. Other mechanism details were also discussed.