Lattice dynamics of novel Heusler alloys MnY2Z (Z=Al and Si)

Abstract

Mn-based Heusler alloys ‘MnY2Z (Z= (Al and Si)) have ‘L21’ crystal structure at the ambient condition of temperature and pressure. MnY2Z have a high melting temperature, shows half-metallic character and shape memory effects where numerous of its applications takes place. In this report, theoretical investigations of the phonon properties of MnY2Z in the cubic phase has been investigated by using density functional theory followed by density functional perturbation theory to comprehend the role of phonons in these alloys. In these calculations, zone center phonon frequency, phonon modes in symmetric directions and phonon density of states are investigated for these alloys. The phonon modes are found to be positive in all symmetric directions indicate the stability of the present alloys in the L21 crystal structure. Additionally, Raman and infrared phonon modes have also been identified for each alloy. The investigated results are interpreted with other existing similar type of Heusler alloys.