First-Principle Calculations on the Structural, Mechanical, and Electronic Properties of Mn₂RuSi and Mn₂RuGe Under Pressure

The second- and third-order elastic constants of the new Inverse Heusler compounds Mn₂RuZ (Z = Si, Ge) are determined from the first-principle calculations combined with homogeneous deformation methods. In terms of the second- and third- order elastic constants, the effective second-order elastic constants of Mn₂RuZ (Z = Si, Ge) are also presented. Besides, the pressure dependence of the brittle/ductile properties, elastic anisotropy factor, Young's modulus, and Debye temperature is further investigated. It is found that both Mn₂RuSi and Mn₂RuGe display ductile nature at ground state and Mn₂RuGe has better ductility than Mn₂RuSi under different pressures. This phenomenon is improved by the Young's modulus. Finally, the density of states of Mn₂RuZ (Z = Si, Ge) under different pressures is also calculated in order to reveal the origin of the effect of pressure on the the ductility of Mn₂RuZ (Z = Si, Ge).