New p-type sp-based half-Heusler compounds LiBaX(X = Si, Ge) for spintronics and thermoelectricity via ab-initio calculations

摘要

We have investigated the structural, electronic, magnetic, elastic and thermoelectric properties of the sp-based half-Heusler LiBaX (X = Si and Ge) alloys using the full-potential linearized augmented plane wave method of density functional theory. Two approaches are employed to approximate the correlation-exchange potential, namely the generalized-gradient approximation and the modified Becke-Johnson. Both compounds free of transition metals are ferromagnetic, half metallic with a large spin-flip gaps which are appropriate for Spintronic applications. Their half-metallicity is preserved under large lattice constant and pressure change which make them promising candidates for spintronic devices. The transport properties reveal high figure of merit values making these compounds great thermoelectric candidates. Moreover, the studied half-Heuslers are mechanically stable and both of them exhibit negative formation energy and cohesion which indicate the possibility of synthesizing and stabilizing these cheap and available materials. Up to date, no experimental or theoretical studies have been carried out regarding LiBaSi, while for LiBaGe, thermoelectric properties have not been investigated yet.