Magnetic structure, mechanical stability and thermoelectric properties of Quaternary Heusler Alloys: First-principles calculations

First-principal calculations were performed to investigate the structural, thermodynamic, dynamical, mechanical, electronic, magnetic, and thermoelectric (TE) properties of quaternary-Heusler alloys (QHAs) with the chemical formula of XX′YZ. Here the X, X′, and Y are transition metal atoms, while Z is a main group element. Several alloys were found to have a half-metallic ferromagnetic structure with indirect band gaps, which is promising for future spintronic applications. They also show good TE properties and appreciable figure-of-merit (ZT) values that suggest them as good candidates for future thermoelectric applications. The TE properties of these quaternary alloys were found to exceed the values of the state-of-the-art thermoelectric materials. An example is the ZT value for a quaternary compound was found to be on the order of 1.0 as compared to that of Bi₂Te₃, which is less than 1 at its optimum temperature.