  Ferromagnetic Ni2MnGa-based alloys play an important role in technological
fields, such as smart actuators, magnetic refrigeration and robotics. The
possibility of obtaining large non-contact deformation induced by an external
perturbation is one of its key strengths for applications. However, the search
for materials with low cost, practical fabrication procedures and large signal
output under small perturbing fields still poses challenges. In the present
study we demonstrate that by judicial choice of substitution on the Mn site, an
abrupt magnetostructural transition from a paramagnetic austenite phase to a
ferromagnetic martensite one can be tuned to close to room temperature
achieving large and reproducible strains. The required magnetic field to induce
the strain varies from small values, as low as 0.25 T for 297.4 K and 1.6% of
strain, to 8 T for 305 K and 2.6% of strain. Our findings point to encouraging
possibilities for application of shape memory alloys in relatively inexpensive,
scalable polycrystalline materials.
