Magnetic field induced strain in polycrystalline Ni50Mn29Ga21 ferromagnetic shape memory alloy

Structural, microstructural and magnetic properties of polycrystalline Ni50Mn29Ga21 alloy are studied. Slight variations in processing parameters were employed to get large grain size and multimode twinning in polycrystalline alloy. The polycrystalline alloy shows significantly low detwinning stress of 19 MPa and high magnetic field induced strain of 0.7%. Presence of large grain size with multimode twinning, 7M modulated crystal structure, large magnetocrystalline anisotropy and high saturation magnetization are key factors for observation of large magnetic field induced strain in polycrystalline alloy.