Effect of spin–orbit coupling on opto-electronic and magnetic properties of rare-earth terbium dioxide (TbO₂): first principle calculations

Abstract

A density functional theory calculation via first principle approach of electronic and magnetic properties of f-electron systems is a matter of pronounced challenge in the materials research due to the struggle in simultaneous stability to delight both the localized and itinerant states. In f-electron systems, f-states show a significant part in defining their chemical and physical properties. In the present investigations, spin-polarized electronic and magnetic calculations have been done for TbO₂. We have employed the PBE-GGA and Tb-mBJ exchange correlation functional for the calculation along with the spin–orbit coupling effect. The band gap of TbO₂ ~ 5.8 eV for spin up states with a magnetic moment of ~ 7.0 μ_B per unit cell was estimated using the PBE-GGA exchange correlation which is in well agreement with previous theoretical studies. The maximum absorption and optical conductivity lies within the visible and UV region with refractive index ~ 3.5 at zero photon energy. These properties of TbO₂ show the ferromagnetic semiconductor character. We have also observed the effect of spin–orbit coupling (SOC) on opto-electronic properties of the compound. Density of states and band structure shows the splitting of the f-states of Tb atoms on inclusion of SOC. The overall electronic, magnetic and optical properties of TbO₂ are suitable for its use in solid state and opto-electronic devices.