In-situ Lorentz TEM cooling study of magnetic domain configurations in Ni/sub 2/MnGa

Magnetic domain configurations in the ferromagnetic shape memory alloy Ni/sub 2/MnGa are analyzed by means of Lorentz microscopy and noninterferometric phase reconstruction methods. Domain structures in the cubic phase consist of cross-tie walls in the thinnest portions of the foil, and more complex configurations in thicker regions. At low temperature, the magnetization configurations change as the structure transforms martensitically to a tetragonal phase. A simple model for the magnetization changes is proposed.