A comparison study of the structural, electronic, magnetic and optical properties of yttrium-based Heusler alloys Y 3 Si, Y 2 CrSi and ScYCrSi

The structural, electronic, magnetic and optical properties of the yttrium-based binary Heusler alloy Y 3 Si , ternary Heusler alloy Y 2 CrSi and quaternary Heusler alloy ScYCrSi have been studied by first-principles calculations. The results show that the preferred configurations of Y 3 Si , Y 2 CrSi and ScYCrSi alloys are DO 3 - FM , Hg 2 CuTi − FM and YI − FM configurations, respectively. The Y 3 Si alloy is a conventional metal ferromagnet. While the Y 2 CrSi and ScYCrSi alloys are HM ferromagnets with spin-up band gaps of 0.682 eV and 0.862 eV as well as the HM characters are maintained in the lattice constant ranges of 6.365–7.057 A and 6.029–7.129 A, respectively, ensuring potential applications in spintronics. The total magnetic moments of the Y 2 CrSi and ScYCrSi alloys are all 2 μ B /f .u . , satisfying the Slater-Pauling rule M t = 18 - Z t . Among three alloys considered, the Y 2 CrSi alloy has the lowest static dielectric constant, static reflective index, static refractive index, global maximum energy loss function but the highest maximum imaginary part. The phonon dispersion spectra show both Y 2 CrSi and ScYCrSi alloys are dynamically stable, while the Y 3 Si alloy is dynamically unstable.