Theoretical investigation of the mechanical and thermodynamics properties of the noncentrosymmetric superconductor SrAuSi3

Abstract

The lattice parameters, electronic structures, elastic constants, Vicker's hardness and thermodynamics properties of SrAuSi3 were systematically investigated by using first-principles and the quasi-harmonic Debye model. The calculated lattice parameters are in excellent agreement with the experimental data. The calculated elastic constants Cij reveal that SrAuSi3 is mechanically stable but anisotropic. The elastic anisotropy is further illustrated by the three-dimensional (3D) of bulk modulus and Young's modulus. The polycrystalline elastic modulus: shear modulus, Young's modulus, Poisson's ratio are derived from the obtained single-crystal elastic constants. In addition, the temperature dependence of the expansion coefficient, specific heat and Debye temperature are investigated through the quasiharmonic Debye model. Finally, Using the McMillan formula the Tc ∼ 9.94 K, which is conflicts with the experimental data (1.54 K). Presumably, the Tc suppression phenomenon due to the presence of an antisymmetric spin–orbit coupling (ASOC) as a consequence of the lack of inversion symmetry.