title: Electronic texture of the thermoelectric oxide Na0.75CoO2.
abstract: From 59Co and 23Na NMR, we demonstrate the impact of the Na+ vacancy ordering on the cobalt electronic states in Na0.75CoO2: at long time scales, there is neither a disproportionation into 75% Co3+ and 25% Co4+ states, nor a mixed-valence metal with a uniform Co3.25+ state. Instead, the system adopts an intermediate configuration in which 30% of the lattice sites form an ordered pattern of localized Co3+ states. Above 180 K, an anomalous mobility of specific Na+ sites is found to coexist with this electronic texture, suggesting that the formation of the latter may contribute to stabilizing the Na+ ordering. Control of the ion doping in these materials thus appears to be crucial for fine-tuning of their thermoelectric properties.
authors: Laboratoire de Spectrométrie Physique, UMR5588 CNRS, 38402 Saint Martin d'Hères, France. Marc-Henri.Julien@ujf-grenoble.fr
authors: M-H
authors: MH
authors: Julien
authors: C
authors: C
authors: de Vaulx
authors: H
authors: H
authors: Mayaffre
authors: C
authors: C
authors: Berthier
authors: M
authors: M
authors: Horvatić
authors: V
authors: V
authors: Simonet
authors: J
authors: J
authors: Wooldridge
authors: G
authors: G
authors: Balakrishnan
authors: M R
authors: MR
authors: Lees
authors: D P
authors: DP
authors: Chen
authors: C T
authors: CT
authors: Lin
authors: P
authors: P
authors: Lejay