Non-conventional twins in five-layer modulated Ni-Mn-Ga martensite

We report observation of non-conventional twins (i.e. twins with neither the twinning plane being a lattice plane, nor the twinning direction being a lattice vector) in five-layer modulated martensite of the Ni-Mn-Ga ferromagnetic shape memory alloy. The twins were observed using scanning and transmission electron microscopy, and identified by calculations using the mathematical theory of martensitic microstructures.