Crystallographic orientation of modulated martensite in epitaxially grown Ni–Mn–Ga thin film

• Epitaxial Ni–Mn–Ga thin films were fabricated in MgO(100) substrate.
• The microstructure presents two distinct martensite plate-like zones.
• The local microscopic crystallographic orientation of 7M martensite was investigated by EBSD.
• Each martensite variant group is composed of four twin-related 7M martensite variant.

In this work, local crystallographic orientation of seven-layer modulated (7M) martensite correlated with microstructure in Ni–Mn–Ga thin films was revealed by electron backscatter diffraction. The microstructure of 7M martensite can be classified into two distinct groups, i.e. the low and high relative contrast zones. There are four crystallographically orientated martensite plates in each variant group. Each martensite plate is composed of one 7M martensite variant. In the low relative contrast zone, all the four variants are with their (2 0 20)mono plane nearly parallel to the substrate surface. In the high relative contrast zone, there are two variants with their (2 0 20¯)mono plane nearly parallel to the substrate surface and two variants with their (0 4 0)mono plane nearly parallel to the substrate surface. Crystallographic calculation indicates that the four 7M martensite variants are twin related.