Influence of magnetic field and stress on large magnetic shape memory effect in single crystalline Ni-Mn-Ga ferromagnetic alloy at room temperature

An effect of the magnetic field and mechanical stress on the magnetically controlled total and reversible strain is clarified. A strong magnetic anisotropy was induced due to the preceding complex magneto-mechanical-thermal treatment. It is shown that this treatment strongly affects the magnetization curves and the reversible strain behaviour. Before this treatment, the studied alloy had the field-induced strain of 0,09%, after that - more than 5,3 %. It is the first time when the large value of the reversible strain, more than 2.5%, is obtained during the cycling of the magnetic field. The results are consistent with the change in the intensity of the X-ray diffraction reflections.