The unique characteristic of magnetic field induced phase transformation of NiMnCoIn magnetic shape memory
alloys (MSMAs) lies in the generation of large transformation strains under high constant stress levels. Motivated
by experiments, a constitutive model is proposed to take into account magnetic field induced phase transformation
from austenitic to martensitic phase. The working principle of such materials is described by the deformation
of continua due to mechanical and magnetic forces. The cross coupling of mechanical and magnetic variables is
captured by introducing nonlinear kinematics. In the present work, microstructure dependence of martensitic
phase transformation is taken into account by introducing internal variables into the model. The constitutive
response is derived in a consistent thermodynamic way.