Investigations on the Structural and Magnetic Properties of Ni-FeGa Bimorphs for Magnetostrictive Applications

Magnetostrictive bimorphs consisting of positive and negative magnetostrictive materials such as FeGa and Ni respectively were made in the form of (a) multilayers containing Si/Ni/FeGa and (b) stacking consisting of Ni/Si/FeGa by sputtering technique on Si substrates. While the thickness of the FeGa film was maintained at 200 nm for all the films, Ni films were grown with two different thicknesses, viz., 100 and 200 nm. Magnetostrictive response of these bimorphs was compared with FeGa unimorph deposited on Si. Structural studies indicated FCC and BCC structure for Ni and FeGa films respectively. Magnetization studies showed a decrease in saturation magnetization with increase in Ni content owing to the lower magnetization of Ni when compared to FeGa. Considerable enhancement in tip deflection has been observed in the bimorph structure when compared with pure FeGa film.