X-ray absorption spectroscopy on layered cobaltates Na_xCoO_2

Abstract

Measurements of polarization and temperature dependent soft x-ray absorption have been performed on Na_xCoO_2 single crystals with x=0.4 and x=0.6. They show a deviation of the local trigonal symmetry of the CoO_6 octahedra, which is temperature independent in a temperature range between 25 K and 372 K. This deviation was found to be different for Co^{3+} and Co^{4+} sites. With the help of a cluster calculation we are able to interpret the Co L_{23}-edge absorption spectrum and find a doping dependent energy splitting between the t_{2g} and the e_g levels (10Dq) in Na_xCoO_2.

7 pages, 8 figures

References in corpus (3)

• A different look at the spin state of Co${}^{3+}$ ions in CoO${}_5$ pyramidal coordination
• Raman Phonons and Ageing-Related Surface Disorder in NaxCoO2
• Polarization dependence of x-ray absorption spectra in Na_xCoO_2

Cited by in corpus (7)

• Magnetism and structure of LixCoO2 and comparison to NaxCoO2
• Spin correlations and cobalt charge states: A new phase diagram of sodium cobaltates
• Polarization dependence of x-ray absorption spectra in Na_xCoO_2
• Electronic structure and Fermi surface tolopogy of Na${}_x$CoO${}_2$
• The origin of a${}_{1g}$ and e${}_g$' orderings in Na${}_x$CoO${}_2$
• Evidence for Oxygen Holes due to d-p Rehybridization in Thermoelectric Sr_{1-x}Rh_{2}O_{4}
• Quasiparticle dispersion near the Fermi surface in Na${}_x$CoO${}_2$