Structural, Elastic, Electronic, Magnetic and Optical Properties of Spin Gapless Semiconducting Heusler Alloy Ti2FeSb Using First-Principles Calculations.

Density functional theory has been used to study the structural, elastic, electronic, magnetic and optical properties of Ti₂FeSb Heusler alloy using generalised gradient approximation implemented through the WIEN2k code. The cubic structure of Ti₂FeSb is mechanically stable in the F-43m space group and shows elastic anisotropic properties with ductile nature. Ti₂FeSb shows spin gapless semiconductor behaviour along with an indirect energy band gap (E_G) of 0.10 eV along the Г-Χ in majority spin (γ-spin) band above the Fermi energy level (E_F) and 0.90 eV in the minority spin (δ-spin) band at E_F. The total magnetic moment is 3 µ_B at optimized lattice constant (a_o) 6.32 Å and follows the Slater–Pauling curve for inverse Heusler alloys. Robustness of this material with respect to change in the value of a_o is evident in the constancy of magnetic moment along with retention of the half metallic nature within a lattice variation ±4% from equilibrium value of a_o. Reflectivity, optical conductivity, dielectric function, absorption coefficient and energy loss have also been investigated as a function of incident energy for this alloy. [ABSTRACT FROM AUTHOR]