Electronic structure study of vanadium spinels by using density functional theory and dynamical-mean-field theory (original) (raw)

2017, EPL (Europhysics Letters)

Theoretically, various physical properties of AV2O4 (A=Zn, Cd and Mg) spinels have been extensively studied for last 15 years. Besides of this, no systematic comparative study has been done for these compounds, where the material specific parameters are used. Here, we report the comparative electronic behaviour of these spinels by using a combination of density functional theory and dynamical mean-field theory, where the self-consistent calculated Coulomb interaction U and Hund's coupling J (determined by Yukawa screening λ) are used. The main features, such as insulating band gaps (Eg), degree of itinerancy of V 3d electrons and position of lower Hubbard band are observed for these parameters in these spinels. The calculated values of Eg for ZnV2O4, CdV2O4 and MgV2O4 are found to be ∼0.9 eV, ∼0.95 eV and ∼1.15 eV, respectively, where the values of Eg are close to experiment for ZnV2O4 and MgV2O4. The position of lower Hubbard band are observed around ∼-1.05 eV, ∼-1.25 eV and ∼-1.15 eV for ZnV2O4, CdV2O4 and MgV2O4, respectively, which are also in good agreement with the experimental data for ZnV2O4. The order of average impurity hybridization function of V site are found to be ZnV2O4>MgV2O4>CdV2O4. Hence, the degree of localization of V 3d electrons is largest for CdV2O4 and smallest for ZnV2O4, which is in accordance with our earlier results. Hence, present work shows the importance of material specific parameters to understand the comparative electronic behaviour of these compounds.