Investigation of the half-metallicity signature and pressure-induced physical properties of cubic ACrO3 (A = Si, Ge, Sn) multiferroic by DFT calculation

Abstract

We report a comprehensive first-principles investigation of the structural, electronic, elastic, magnetic, and optoelectronic properties and half-metallicity of ACrO₃ (A = Si, Ge, Sn) with space group Pm3m (no. 221), studied for the first time using density functional theory (DFT) in the pressure range of 0–30 GPa. The tolerance factor reveals that the compounds are cubic phase. SnCrO₃ is structurally stable. The optimized stable magnetic state of the compounds is ferromagnetic, and by applying Born stability criteria for elastic constants, it is found that ACrO₃ (A = Si, Ge, Sn) compounds are mechanically stable over the whole pressure range. The materials’ half-metallic nature is confirmed by band gaps and density of states (DOS) studies, which show that the majority spin-channel states are conducting, while the minority spin-down levels are semiconducting. Moreover, we calculated the bulk (B) and shear modulus (G), Poisson's ratio (v), Cauchy pressures, anisotropy (A), plasticity (B/C₄₄) and Young's modulus (E). The plasticity and bond distortion decrease as pressure increases. SnCrO₃ and SiCrO₃ are brittle at pressures from 0 to 10 GPa, and become ductile in the pressure range of 10 to 30 GPa. In contrast, GeCrO₃ is ductile over the whole pressure range. The spin-polarized band structure reveals that ACrO₃ (A = Si, Ge, Sn) maintains a direct band gap (R–R) over the whole pressure range. Several optical properties, including dielectric function, reflectivity, refractive index, conductivity, and absorption coefficient, are also calculated. It is revealed from the real part of the dielectric function that the compounds are optically metallic at lower energy and semiconducting at higher energy, and the plasma frequency rises with pressure. The optical properties and half-metallic response show that ACrO₃ (A = Si, Ge, Sn) has intriguing properties for spintronic and optoelectronic devices.