Magnetic Properties and Martensite Structures of Ni₅₀Mn₂₈Ga₂₂ Ferromagnetic Shape Memory Alloy

Abstract

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.