First-Principles Calculations to Investigate Structural, Electronic, Optical and Magnetic Properties of Pyrochlore Oxides Eu2Tm2O7 (Tm = Hf, Sn, Zr) for Energy Applications

Abstract

Three newly designed pyrochlore oxides, Eu2Tm2O7 (Tm = Hf, Sn, Zr), are analyzed for their magnetic, optical and electronic properties using ab-initio calculations within the context of density functional theory (DFT). We can refer these compounds as direct bandgap materials because there is a very slight difference between the height of bands at the Γ- and M-point. It is observed that bandgap engineering can be performed by replacing Hf with Sn and Zr. It is observed from total density of states (TDOS) plots that shape and height of curves is not the same in spin up and spin down channels, showing significant magnetic moment in these compounds. It is evident from magnetic properties that a major portion of total magnetic moment (mtot) comes from Eu-atoms. In all compounds, the magnetic moment of O, Hf, Sn and Zr atoms is negative, whereas the magnetic moment of Eu-atoms is positive, showing their antiparallel arrangement. In both spin channels, significant absorption of the incoming photons is also shown by these compounds in the ultraviolet (UV) region. We can conclude on the basis of Rω that these compounds can be utilized in applications such as anti-reflecting coatings. These compounds are potential candidates for photovoltaic applications, such as solar cells, due to efficient absorption of incoming photons in visible and UV regions.