The twinned magnetic microstructure of Ni2MnGa ferromagnetic shape-memory alloy was investigated using high-resolution nanoscale modulus mapping. A surprisingly fine near-surface nanoscale sub-structure of closure magnetic twin variants was observed. The lateral distance between adjacent closure variants was found to be 100nm. The small size of twin variant prisms provided a unique opportunity to evaluate the twin boundary energy by considering the competition between the magnetic field and interface energies. An estimate indicated a relatively small twin boundary energy of 3mJ/m2, which suggested the ability of Ni2MnGa to form nanoscale structures of magnetic twin variants.

Modulus Mapping of Nanoscale Closure Variants in Ni-Mn-Ga. Y.Ganor, D.Shilo: Applied Physics Letters, 2008, 93[3], 031905