Kondo-like resonance in ZnO:Eu

摘要

Doping ZnO with Eu results in the hybridization of the f atomic orbitals of the Eu with the bands of the host material. The strongest interaction turns out to be with the oxygen s-p band. This hybridization manifests itself as a Kondo-like resonance, namely, the appearance of a narrow resonant f band close to the Fermi level. Our aim in the present work is to calculate the electronic structure of ZnO:Eu in which the lanthanide ion replaces one of the Zn ions inducing a geometric relaxation on the system. We have used two reliable crystal electronic structure codes for our calculation. The program WIEN2k [Blaha, P., et al. WIEN2k, An Augmented Plane Wave + Local Orbitals Program for Calculating Crystal Properties, 2001] allows us to include the effects of the f the GGA + U model (generalized gradient approximation plus U) for the relaxed configuration. On the other hand, the program CRYSTAL06 [] allows us to monitor the charge of the Eu ion using a judicious mix of the Hartree-Fock nonlocal exchange term with the density functional exchange-correlation potential. Results are presented for the density of states (both the total and the partial contribution from the f electrons), as well as maps of the spin density around the Eu ion, both clearly showing the presence of the resonant f bands.