Theoretical Study of the Structural Stability, Electronic and Magnetic Properties of Half-Metallic Ferromagnetism Cr2NbZ (Z = As, Sb)

Based on first principles calculation, a systematical investigation has been performed to study the structural, electronic, mechanical and magnetic properties of the new Heusler alloys of Cr2NbZ (Z = As, Sb), using the full-potential linearized augmented plane wave (FP-LAPW) method with the Generalized Gradient Approximation (GGA) within the framework of density functional theory (DFT). It is found that the L21-type (AlCu2Mnl-type) structure is energetically more stable than the X-type (CuHg2Ti-type) structure due to the lower total energy. Moreover, several mechanical properties of Cr2NbAs and Cr2NbSb have been studied and its mechanical stability is also verified. The calculated electronic band structure reveals the metallic nature of Cr2NbZ (Z = As, Sb) and its total magnetic moment of 2µB is mainly contributed by Cr atom from strong spin splitting effect, as indicated with the distinctive distributions of the density of states in two spin directions. We have found that the spin polarization (SP) equals 100% for Cr2NbAs and Cr2NbSb, our materials has a half -metallic state. In addition the temperature and pressure effects on the bulk modulus, heat capacities, Debye temperature and entropy are computed and discussed in details. This theoretical study provides detailed information about the Cr2NbZ (Z = As, Sb) compounds from different aspects and can further lead some insight on the application of this material.