Insight into the structural, electronic, mechanical, magnetic and thermodynamic properties of the new half-metallic ferromagnetic full-Heusler alloys Cr2YZ (Z = Si, Ge, Sn) from initio calculations

Structural, electronic, magnetic and mechanic properties of Cr(2)YZ (Z = Si, Ge and Sn) Heusler alloys have been analyzed by means of first-principles calculations on the basis of density functional theory. It is found that the L2(1)-type (AlCu(2)Mnl-type) structure is energetically more stable than the X-type (CuHg2Ti-type) due to the lower total energy. The calculated lattice constants for Cr2YSi, Cr2YGe and Cr2YSn are 6.3500 angstrom, 6.4333 angstrom and 6.6607 angstrom, respectively. For mechanical properties, shear modulus, Young's modulus, elastic constants, Poisson's ratio and shear anisotropy factor have studied. Their obtained values reveal that these compounds are mechanically stable. Analysis of the electronic band structures and density of states for Cr2YSi, Cr2YGe and Cr2YSn revealed that the spin-up bands are metallic, whereas the spin-down bands exhibit gaps of 0.712 eV, 0.739 eV and 0.735 eV, respectively. Several mechanical properties of Cr(2)YZ (Z = Si, Ge and Sn) have been studied, and its mechanical stability is also verified. The total magnetic moment of 5.00 mu(B) is mainly contributed by the Cr atom. Furthermore, the thermodynamic properties, such as the heat capacity C-V, the thermal expansion coefficient alpha, bulk modulus beta and the Debye temperature theta(D), are computed by using the quasi-harmonic Debye model within the same pressure range at a series of temperature from 0 to 1400 K.