Role of covalent hybridization in martensitic structure and magnetic   properties of shape memory alloys: the case of Ni50Mn5+xGa35-xCu10
  We have investigated the impact of covalent hybridization on martensitic structure and magnetic properties of Ni50Mn5+xGa35-xCu10 shape memory alloys. We found that the lattice distortion ((c-a)/a) of L10 martensite monotonously changes with the substitution of Mn for Ga atoms and shows a kink behavior at Ga(at.%)= 25 due to the weakened covalent effect between main-group and transition-metal atoms. Moreover, owing to the competition between covalence hybridization and magnetic ordering of introduced Mn atoms, the molecular magnetic moment and Curie temperature coincidently show maximums at Ga(at.%)=25 as well. These behaviors are closely associated with corresponding changes of the strength of covalent hybridization. The results therefore suggest that careful control of the concentration of main-group atoms in Heusler alloys can serve as an additional general tuning parameter for searching new multifunctional materials. 
G. J. Li, E. K. Liu, H. G. Zhang, Y. J. Zhang, G. Z Xu, H. Z. Luo, H.   W. Zhang, W. H. Wang, and G. H. Wu
cond-mat.mtrl-sci