Structural configuration and phase stability in full Heusler alloys Cr2ZnSi and Cr2ZnGe

Abstract In Heusler compounds, structural configuration and phase stability are essential for determining their properties. Under this framework, we have systematically investigated the atomic configuration in the full Heusler compounds Cr2ZnSi and Cr2ZnGe and their electronic, magnetic, mechanical and dynamic properties. Both L21-type and XA-type structural configurations have been investigated and the corresponding equilibrium lattice constants in cubic phase have been determined, which are in good consistence with previous studies. Mechanical and dynamic properties have been further investigated and results show that the L21-type structures for both Cr2ZnSi and Cr2ZnGe are both mechanically and dynamically stable whereas the XA-type structures are not. And, strong elastic anisotropy is also revealed with the calculated directional dependent Young’s modulus and shear modulus. Afterwards, the tetragonal phase has been considered and results show that tetragonal XA-type structure can further reduce the total energy with regard to the cubic phase. The minimum total energies under tetragonal phases at c/a ratio of 1.31 and 1.41 are even lower than that of the cubic L21-type structure for both Cr2ZnSi and Cr2ZnGe, respectively, and their mechanical and dynamic stabilities have also been confirmed. This detailed investigation about the structural configuration and phase stability in full Heusler alloys Cr2ZnSi and Cr2ZnGe from different perspectives can be important and helpful for the related studies and inspire other relative works.