The Observation of Martensite and Magnetic Domain Structures in Ni₅₃Mn₂₄Ga₂₃ Shape Memory Alloys by Scanning Electron Acoustic Microscopy and Scanning Thermal Microscopy

We present observations of martensite variants and ferromagnetic domain structures of Ni₅₃Mn₂₄Ga₂₃ ferromagnetic shape memory alloys with a pure tetragonal martensitic phase by using scanning electron acoustic microscopy (SEAM) and scanning thermal microscopy (SThM). Electron acoustic images show a polycrystalline morphology with martensite variants. Direct coincidence between crystallographic martensitic twin variants and magnetic domains is found. A domain-like structure, obtained by SThM, is firstly reported, and then confirmed by magnetic force microscopy (MFM). The experimental results will be helpful for investigating the local thermal properties of ferromagnets and understanding the relationship between martensite variants and magnetic domains.