Prediction of some physical properties in new half Heusler alloy NbAgSi

Abstract

A first principle investigation of structural, dynamical, mechanical, thermodynamic and electronic properties of ‘NbAgSi’ alloy was performed using the density functional theory. Among ‘α’, ‘β’, and ‘γ’ structural phases, ferrimagnetic ‘β’-phase was found to be the most favorable ground state. The structural and dynamical stabilities of the compound were determined by the formation/cohesive energies. The dynamical stability was further strengthened by positive phonon frequencies, observed in the phonon dispersion curves. The mechanical properties of the sample material were explored using the elastic constants to explore its mechanical applications. To include the effect of highly correlated system Nb, the Hubbard parameter (U) was determined and incorporated in the calculations to predict the half-metallic behavior of the sample alloy correctly. The inclusion of the U term had a significant effect on the electronic and magnetic properties of the system. The material was found to possess anisotropic character with ductile behavior. The thermodynamic properties were also measured over the temperature range 0 – 500K under different pressures. The optical phonon modes were found to be a mixed character of Raman and infrared active. The electronic and bonding behavior were analyzed from the Fermi surface, charge density plot and electron localized function. The charge transfers between the atoms were investigated using the Bader charge technique. The results presented in the present manuscript open the possibility of the sample material as a promising candidate for spintronic applications.