Half-metallic ferromagnetism in Be1−x V x Te alloys: an Ab-initio study

Abstract

First-principles calculations of the structural, elastic, electronic, magnetic and thermodynamic properties of zinc blende Be1−x V x Te alloys (x = 0, 0.25, 0.50, 0.75 and 1) based on spin-polarized density functional theory are performed using full-potential augmented plane wave method, within the spin generalized gradient approximation for the exchange–correlation potential. The equilibrium structural parameters such as lattice constant (a 0 ), bulk modulus (B 0 ) and first pressure derivative of bulk modulus (\( B^{\prime } \)) are optimized for all alloys. The elastic constants C 11, C 12, C 44 and anisotropy coefficients are also estimated. The calculations of the band structure and the density of states demonstrate that all Be1−x V x Te (x = 0.25, 0.50, 0.75 and 1) alloys are complete half-metals. The investigation of the band structure and the density of states demonstrate that Be0.75V0.25Te alloy is entirely half-metal, whereas Be0.50V0.50Te and Be0.25V0.75Te alloys are nearly half-metal. The estimation of the s(p)–d exchange splitting constants N 0α (conduction band) and N 0β (valence band), as obtained through the density of states, have been used to indicate the magnetic behavior of the compounds. From the total magnetic moment, it is observed that the p–d hybridization reduces the local magnetic moment of V atom from its free space charge of 3µ B and generates small local magnetic moments on the nonmagnetic Be and Te sites. Lastly, based on the quasi-harmonic Debye model, the obtained macroscopic thermodynamic properties, such as thermal expansion coefficient, heat capacities and Debye temperate, are presented in detail.