Theoretical Study of the Spinel Structure of CuCr2O4 in the Tetragonal Phase Using Density Functional Theory

We report a detailed theoretical study of ternary spinel oxides CuCr₂O₄ with tetragonal I4₁/amd structures by means of density functional theory (DFT). The calculations were performed using two approximations to DFT, namely, the local density approximation (LDA) and the generalized gradient approximation (GGA), both in the spin-polarized version. For LDA, we used the Ceperley-Alder exchange-correlation potential, whereas for the GGA calculations, we used the Perdew-Burke-Ernzerhof (PBE) scheme. We optimized the crystal structures using a pseudopotential plane wave method and analyzed on the basis of the density of states (DOS), partial density of states (PDOS), and electronic band structure. Indeed, it is a useful method to predict the crystal structures of CuCr₂O₄. The PDOS of Cu, Cr, and O revealed that the Cr cation is the dominant source to study the magnetic properties of CuCr₂O₄. Spin polarization calculations performed for CuCr₂O₄, and DOS show that there is a large spin splitting between the spin up down channels near the Fermi level, confirming p-d hybridization. The theoretical calculated magnetic moment is slightly higher than the experimental results. It was concluded that the optimized GGA lattice parameter agrees much better with the experimental findings than the LDA one. The valence and conduction bands overlapped each other at the Fermi level, indicating the metallic nature of CuCr₂O₄. The charge density difference maps indicate that Cu–Cr bonds are stronger than Cu–O. The obtained results were compared with experimental values and a good agreement with them was found. The results of the present study could be used in a future analysis of thermodynamical, optical and elastic properties of this compound.