First principle studies on structure, magneto-electronic and elastic properties of photovoltaic semiconductor halide (RbGeI3) and ferromagnetic half metal oxide (RbDyO3)

Abstract

By using density functional theory (DFT) in terms of ab-initio investigation, we examined the structural, electronic and magnetic properties of cubic, halide perovskite (RbGeI3) and oxide perovskite (RbDyO3) for the first time. Structural stability of cubic RbGeI3 and RbDyO3 compounds were determined by optimizing the structure in ferromagnetic (FM), non-magnetic (NM), and Anti-ferromagnetic (AFM) phases by using PBE generalized gradient approximation (GGA) functional to find the exchange-correlation potential. From structural optimizations, the nonmagnetic phase of RbGeI3 and the ferromagnetic phase of RbDyO3 was observed to be stable. From the stability curve, we calculated the equilibrium lattices, bulk moduli and their pressure derivatives and equilibrium volume. Moreover, the calculation of tolerance factor for these compounds (τ ≈1) demonstrates the formation of the cubic perovskite structure. The spin magnetic moments of these compounds have been obtained to explore the magnetic properties of RbDyO3. Since, RbGeI3 is nonmagnetic material with zero magnetic moment as also observed from the structural optimization. Rare earths like Dysprosium (Dy) possess strongly localized f-electronic states which are responsible for their strong magnetic properties and other delocalized f-electron states arising from the hybridization of p-d states which determine the electronic properties within the material. The latter situation suits well for RbGeI3 compound. We report a detailed analysis of the different ground state properties for the two compounds using GGA and GGA-modified Becke–Johnson computational approaches.