Tailoring structural, electronic, optical, and magnetic properties of rare-earth gallates RGaO$_3$ (R = Ho, Er, Tm) via first-principles investigations

Abstract

Ab initio calculations of cubic perovskites RGaO$_3$ (R = Ho, Er, Tm) were performed using the full-potential linearized augmented plane wave (FP-LAPW) method within the framework of density functional theory (DFT). We investigated their structural, electronic, magnetic, and optical properties in detail. In the optimized configurations, the lattice constants ranged from 3.83 to 3.85 A. The electronic band structures indicate that ErGaO$_3$ is semiconducting, whereas HoGaO$_3$ and TmGaO$_3$ exhibit half-metallic behavior, probably due to the interaction of spin-orbit coupling with the electronic states near the Fermi level. Optical response of half-metallic compounds (HoGaO$_3$,TmGaO$_3$) is strongly governed by their spin polarization electronic structure. The semiconducting spin channel absorbs ultraviolet photons, while metallic or small gap channel interacts with infrared light. This dual behavior enables spin selective optical excitation, relevant for spintronics and optoelectronics applications. These compounds show high surface reflectivity, with TmGaO$_3$ achieving a maximum reflectivity of 69%. Moreover, their optical conductivity mainly occurs at higher energies, indicating suitability for high-energy optoelectronic applications. The calculated magnetic moments suggest a robust ferromagnetic character across this series.