Investigation of half-metallicity and magnetism of (Ni/Pd/Ru) ZrTiAl quaternary Heusler alloys for spintronic applications

The half-metallic behaviour, magnetic, mechanical and thermal properties of LiMgPdSn-type (Ni/Pd/Ru) ZrTiAl alloys were investigated by using ab initio calculations. The generalized gradient approximation in the form of PBE was utilized to treat the exchange-correlation energy for the entire calculations and GGA + U was utilized for strongly correlated electrons of ZZrTiAl (Z = Ni, Pd, Ru) compounds during electronic structure calculations. We used the values of U as 2eV for (Ni/Pd/Ru), 1eV for Zr and 1.5eV for Ti elements. The investigated lattice parameters and magnetic properties of the PdZrTiAl alloy are in close agreement with theoretical results. The estimated cohesive energy confirms the chemical structural stability of ZZrTiAl compounds. The total magnetic moments of (Ni/Pd/Ru) ZrTiAl alloys are 3.00, 3.01 and 1 mu(B)/f.u., satisfying the SP rule. Within GGA + U, ZZrTiAl alloys show half-metallic nature with wide band gaps of 0.56 eV, 0.57eV and 0.78 eV respectively confirming applications in spintronic devices. The elastic constants reveal that the ZZrTiAl alloys are mechanically steady and the B/G ratio confirmed that the alloys considered are ductile in nature, which is consistent with Poisson's ratio. In addition, the Debye temperature, melting temperature and Gruneisen parameter were investigated by using average sound velocity and elastic symmetry.