Tailoring the magneto-electronic and optical properties of cobalt doped strontium titanate by first-principles calculations

Abstract

Ferromagnetic semiconductors or half metals offer strategic advantage in spintronic applications due to their robust stray fields and ultrafast magnetic dynamics. Controlling their magnetization and readout of their magnetic state are essential for these applications but remain challenging. Herein, we present a density functional theory (DFT) based full potential linearized augmented plane wave (FP-LAPW) analysis of the magneto-optical properties of novel and most widely studied diamagnetic SrTiO3 (STO) doped with cobalt. Pure STO is non-magnetic wide band gap (3.25 eV) semiconductor. Our study shows that versatile transport and magnetic properties can be obtained in CoxSr1-xTiO3, ranging from magnetic semiconductor to half metallic ferromagnetic nature depending upon the dopant's concentration. Spin resolved electronic properties and non-zero values of calculated magnetic moments for doped supercells reveal that Co0·125Sr0·875TiO3 and Co0·25Sr0·75TiO3 are good DMSs while Co0·5Sr0·5TiO3 and Co0·75Sr0·25TiO3 are half metallic ferromagnets. The analysis of band structures and density of states reveal that partially filled Co-3d and O-2p states show hybridization. Moreover, calculated optical conductivity lie in the visible region of the order of 103 (Ω cm)−1 while reflectivity in this region is minimum. Our findings demonstrate Co doping as a powerful approach to control the magneto-optoelectronic physics in STO, which will stimulate further experimental research with promise for tailored magnetic and optoelectronic properties in Co doped STO systems.