Abstract
The electronic structure of delafossite type oxides AFeO2 (A = Ag, Cu) has been calculated using the full potential linearized augmented plane wave (FP-LAPW) method within the local spin density approximation (LSDA), Perdew−Burke−Ernzerhof (PBE-GGA), and Engel−Vosko (EV-GGA) generalized-gradient approximations. It was found that the EV-GGA provides a more realistic description of the electronic structure and the optical properties of AFeO2 than PBE-GGA or LSDA. The influence of electron correlations has been considered within the PBE-GGA+U and LSDA+U methods. The effective Hubbard U, Ueff, has been derived on the basis of an ab initio constraint calculation and by comparison with X-ray emission spectra. The energy band gap of AFeO2 within the PBE-GGA+U is found as a charge-transfer gap between O-2p to Fe-3d states. The theoretical optical band gaps Δ0 = 1.30, Δ1 = 2.06, and Δ2 = 3.20 eV for CuFeO2 are quite compatible with experimental data. We have predicted an optical band gap Δ0 = 1.90 eV for AgFeO2, a...
Published Version
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