Quantitative model of large magnetostrain effect in ferromagnetic shapell memory alloys

A quantitative model describing the large magnetostrain effect observed in several ferromagnetic shape memory alloys such as Ni2MnGa is briefly report ed. The paper contains an exact thermodynamic consideration of the mechanic al and magnetic properties of similar types of materials. As a result, the basic mechanical state equation including magnetic field effect is directly derived from a general Maxwell relation. It is shown that the magnetic fie ld induced deformation effect is directly connected with the strain depende nce of magnetization. A simple model of magnetization and its dependence on the strain is considered and applied to explain the results of experimenta l study of large magnetostrain effects in Ni2MnGa.