  In the present work, the aspects of magnetic and structural properties of
Ni-Mn-Ga alloys are described in the framework of fist-principles approach and
mapped into ternary composition diagrams. The stable atomic arrangement and
magnetic alignment for compositions with cubic austenite and tetragonal
martensite structures across phase diagrams are predicted. It is shown that Ni-
and Ga-rich compositions possess the regular Heusler structure in contrast to
Mn-rich compositions with inverse Heusler structure as favorable one.
Compositions with unstable austenite structure are concentrated in the left and
right sides of diagram whereas compositions with unstable martensite structure
are located in the low-middle part of diagram. The magnetic phase diagrams
showing regions with the ferromagnetic order and the complex ferrimagnetic
order for austenitic and martensitic compositions are obtained. The results of
calculations are in a good agreement with available experimental data.
