Magnetic Properties and Martensite Structures of Ni50Mn28Ga22 Ferromagnetic Shape Memory Alloy

Magnetic properties and martensite structures of Ni50Mn28Ga22 ferromagnetic shape memory alloy (FSMA) haven been investigated by physical properties measurement system (PPMS), magnetic force microscope (MFM) and transmission electron microscope (TEM) in the present paper. Magnetization-magnetic field (M–H) curves and MFM images show that the martensite has stronger magnetic anisotropy than the parent phase. The typical martensite with twin substructures is observed in Ni50Mn28Ga22 alloy, while another type martensite substructure showing stripe like morphology is also found. It is assumed that such martensite structure may affect the magnetic field induced strain (MFIS) of Ni50Mn28Ga22 alloy.