Figure 4
From: Modulations in martensitic Heusler alloys originate from nanotwin ordering
The magnetic origin of the interaction energy. Magnetic exchange constants Jij within (a) the tetragonal NM martensite with c/a|NM=1.25 and (b) the optimised 4O demonstrating the decrease of magnetic frustration in 4O. Exchange constants between pairs of Mn atoms are marked by blue circles and between Mn and Ni atoms by red squares. Positive values conform with the ferromagnetic order and negative values are frustrated and increase the energy. The saturation of the colours corresponds to the occurrence N of the respective interaction relative to one formula unit Ni2MnGa, indicating their impact on the total energy. For clarity, the multiplicity of selected interactions is marked explicitly by small numbers close to the symbols.
