Magnetic-field-induced strain assisted by tensile stress in L1 martensite of a Ni–Fe–Ga–Co alloy

Magnetic-field-induced strains larger than 2% have been obtained in the nonlayered L10 martensite of a Ni49Fe18Ga27Co6 single crystal, under an assisting tensile stress around 16 MPa and fields below 15 kOe. In martensitic samples previously compressed, application of a constant tensile stress along the same axis together with a perpendicular magnetic field produces the elongation of the sample, as one of the variants rotates its c axis from the field direction to the stress-axis direction. An estimated magnetostress of ∼0.8 MPa is in good agreement with the theoretical value given by the ratio of magnetocrystalline anisotropy constant and twinning shear.