One-dimensional dynamics of the d electrons in alpha '-NaV2O5 - art. no. 165113

We have studied the electronic properties of the ladder compound alpha'-NaV 2O5, adopting a joint experimental and theoretical approach. The momentum-d ependent loss function was measured using electron energy-loss spectroscopy in transmission. The optical conductivity derived from the loss function b y a Kramers-Kronig analysis agrees well with our results from local spin de nsity approximation (LSDA) + U band-structure calculations upon application of an antiferromagnetic alignment of the V 3d(xy) spins along the legs and an on-site Coulomb interaction U between 2 and 3 eV. The decomposition of the calculated optical conductivity into contributions from transitions bet ween selected energy regions of the density of states reveals the origin of the observed anisotropy of the optical conductivity. In addition, we have investigated the plasmon excitations related to transitions between the van adium states within an effective 16-site vanadium cluster model. Good agree ment between the theoretical and experimental loss functions was obtained u sing the hopping parameters derived from the tight-binding fit to the band- structure and moderate Coulomb interactions between the electrons within th e ab plane.