First-principles calculations to investigate structural, elastic, electronic and magnetic properties of novel d0 half metallic half Heusler alloys XSrB (X=Be, Mg)

• Published in: Intermetallics 2022-01, Vol.140, p.1, Article 107392
• Main Authors: Abada, A., Marbouh, N., Bentayeb, A.
• Format: Article
• Language: English
• Subjects: Constants; d0 half-metals; Density functional theory; Elastic properties; Electronic properties; Electronic structure; Energy gap; Ferromagnetism; First principles; Formation energy; Free energy; Half Heusler alloys; Heat of formation; Heusler alloys; Lattice parameters; Magnetic moments; Magnetic properties; Mathematical analysis; Metallicity
• ISSN: 0966-9795; 1879-0216
• DOI: 10.1016/j.intermet.2021.107392

The structural, elastic, electronic properties and magnetism of new d0 half Heusler alloys XSrB (X = Be, Mg) were investigated by means of first-principles calculation based on the density functional theory (DFT). The exchange-correlation functional is treated by the generalized gradient approximation proposed by Perdew–Burke–Ernzerhof (GGA-PBE). The Tran-Blaha modified Becke-Johnson (TB-mBJ) exchange potential, which can compute accurately the band gap of solids, is adopted to improve the calculations of the electronic structure and magnetic properties. We found that the two alloys are energetically and mechanically stable in the α phase presenting ductile nature with negative cohesive energies. It was found that MgSrB compound can be experimentally synthesized because of its negative formation energy. The two compounds are half-metallic ferromagnets with total magnetic moment of 1.000 μB per formula unit, in well agreement with Slater-Pauling rule (Mtot = (8 – Ztot) μB). Our calculations show that BeSrB and MgSrB have majority band gaps of 1.024 eV (1.387 eV) and 0.831 eV (1.277 eV) with half-metallic gaps of 0.165 eV (0.613 eV) and 0.311 eV (0.626 eV), respectively, by GGA-PBE (TB-mBJ). The origin of these gaps is well discussed. It was also found that BeSrB and MgSrB are robust half-metallic alloys with respect to the variation of lattice constants. They kept their half-metallicity in relatively wide range of lattice constants of 5.90–7.00 Å and 6.18–7.28 Å, respectively. The obtained results reveal also that BeSrB and MgSrB compounds are considered as nearly gapless half-metallic ferromagnets for lattice parameters range of 7.03–7.88 Å and 7.50–8.40 Å, respectively, which makes them promising candidates for potential applications. •The structural and mechanical stabilities of the half Heusler alloys BeSrB and MgSrB are confirmed in the α-phase within the C1b -type structure.•The negative formation energy of MgSrB alloy confirms the possibility of its synthesis experimentally.•The half Heusler alloys BeSrB and MgSrB are half-metallic ferromagnets with total magnetic moment of 1.000 μB per formula unit using GGA-PBE and TB-mBJ approachs.•The half-metallicity mainly originates from the spin polarization of the 2p states of bore atom.•BeSrB and MgSrB alloys kept their half-metallicity in relatively wide lattice constants ranges of 5.90–7.00 Å and 6.18–7.28 Å, respectively.