Magnetic and mechanical properties of Ni-Mn-Ga single crystals

A method is presented to obtain large field-induced strain in NiMnGa-oriented single crystals. The magneto-mechanical results here presented are measured on an oriented single crystal of composition Ni/sub 50/Mn/sub 29.5/Ga/sub 20.5/ with {100} and {110} faces. The method relies on the stress-strain characterization of the sample. Once a repeatable pseudoplastic behavior is obtained by a sequence of mechanical cycles and thermal treatments, a combination of stress and magnetic field is applied, achieving a 1.2% irreversible strain by applying a 450 kA/m magnetic field along the [100] direction and maintaining a [100] stress value to about 12.5 MPa.