The structural, magnetic, electronic, and mechanical properties of the full Heusler alloys Ti₂CoTl_1−xPb_x (x = 0.00, 0.25, 0.50, 0.75, 1.00)

We investigate the structural, magnetic, electronic, and mechanical properties of the full Heusler alloys (FHAs) Ti₂CoTl_1−xPb_x (x = 0.00, 0.25, 0.50, 0.75, 1.00) using first-principles calculations. The FHAs Ti₂CoTl_1−xPb_x have the half-metallic characters within lattice constant regions 5.799–6.707, 5.749–6.821, 5.749–6.982, 5.789–7.115, and 5.976–6.943 Å for x = 0.00, 0.25, 0.50, 0.75, and 1.00, respectively. The negative formation energy, positive cohesion energy, and higher than room temperature Curie temperature indicate that the FHAs Ti₂CoTl_1−xPb_x are thermodynamically stable and can be used in spintronics and magnetoelectronics. The total magnetic moment per formula unit ${\mu }_{\text{t}}$ of the FHAs Ti₂CoTl_1−xPb_x satisfies the Slater–Pauling rule ${\mu }_{\text{t}}=Z{}_{\text{t}}-18$, where $Z_{\text{t}}$ represents the total number of valence electrons per formula unit. With increasing Pb atom concentration x, the band structures in both spin-up and spin-down channels move toward low energy region, but the spin-down indirect band gap $E_g^{\downarrow }$ increases. In addition, the calculated elastic constants and elastic modulus indicate that the FHAs Ti₂CoTl_1−xPb_x have mechanical stability, as well as ductility and strong resistance to fracture and plastic deformation.