Fabrication conditions and transformation behavior of epitaxial Ni-Mn-Ga thin films

Epitaxial Ni-Mn-Ga films have been grown onto heated substrates by sputtering. Their chemical composition depends on the sputtering argon pressure. Representative epitaxial films of Ni52.3Mn26.8Ga20.9, 0.5 mu m-thick, transform martensitically at about 120 A degrees C, accompanied by sharp changes in the lattice parameter and resistivity, and orders ferromagnetically below 98A degrees. The observed high transformation temperature, orthorhombic martensitic structure, twinning mode and film morphology, indicate a potential multifunctional behavior of the film, such as high-temperature shape-memory effect and magnetic field actuation.