Twin boundary motion and magnetic domain distribution investigated by optical polarization microscopy

An overview of optical studies of magnetic and structural transformation in magnetic shape memory materials is given. The magnetic domain behavior and the motion of twin boundaries in single crystalline bulk samples of the shape memory alloy NiMnGa are investigated by optical polarization microscopy and magnetic indicator film technique. During stress induced twin boundary motion the magnetization reversal takes place by rotation of magnetization, leading to a total rearrangement of the magnetic domain distribution. Time-resolved studies of twin boundary motion induced by pulsed magnetic fields show that the distance traveled by the twin boundary is enhanced with increasing sample temperature. An overview of these and complementary experiments and the obtained results will be given.