Opto-electronic and thermoelectric properties of XMgY (X=Li, Na; Y=Al, Ga) alloys: GGA and SCAN based approaches

The half Heusler alloys are important class of materials which are utilized for memory as well as the spintronic devices. The thermoelectric response calculations are also reported for Heuslers alloys. In this research work, electronic dispersion curves, thermoelectric and optical parameters of XMgY (X=Li, Na/Y=Al, Ga) half Heuslers have been investigated by employing the pseudopotential approach along side the Boltzmann transport theory. The XMgY (X=Li, Na/Y=Al, Ga) were reported stable in C1b type structure by energy-volume optimization, Born stability criteria on elastic constants and positive phonon modes in full zone in phonon dispersion curves by Afaq et al. Both the SCAN and Generalized Gradient Approximation proved these alloys metallic in nature. To understanding the complex phenomenon of electron flow inside a material, Fermi surfaces are studied and discussed. The different thermoelectric response parameters are computed in temperature range 300 to 1200 K. The comprehensive analysis of imaginary part of dielectric constant predicts the utility of these alloys in sensors and opto-electronic devices.