Growth and magnetic control of twinning structure in thin films of Heusler shape memory compound Ni2 MnGa

Twin structure engineering in sputtered films close to the Heusler stoichiometry Ni2 MnGa (001) is used to demonstrate temperature and magnetic control of the phase transformation behavior. A custom heating apparatus integrated with a commercial microscope allows the observation of the austenite-martensite transition in epitaxially clamped films. Intermartensitic twin boundaries on cantilevers released from the epitaxial strain by focused ion beam etching are shown to move in response to an applied magnetic field with a strength of 0.6 T. We also report the observation of two coexisting twin morphologies. © 2008 American Institute of Physics.