59Co NMR evidence for charge and orbital order in the kagome like structure of Na2/3CoO2

Abstract

We report a complete set of ${}^{59}$Co NMR data taken on the $x=2/3$ phase of sodium cobaltates Na${}_x$CoO${}_2$, for which we have formerly established the in plane Na ordering and its three dimensional stacking from a combination of symmetry arguments taken from Na and Co NQR/NMR data. Here we resolve all the parameters of the Zeeman and quadrupolar Hamiltonians for all cobalt sites in the unit cell and report the temperature dependencies of the NMR shift and spin lattice relaxation $T_1$ data for these sites. We confirm that three non-magnetic Co${}^{3+}$ (Co1) are in axially symmetric positions and that the doped holes are delocalized on the nine complementary magnetic cobalt sites (Co2) of the atomic unit cell. The moderately complicated atomic structure resumes then in a very simple electronic structure in which the electrons delocalize on the Co2 kagomé sublattice of the triangular lattice of Co sites. The observation of a single temperature dependence of the spin susceptibilities indicates that a single band picture applies, and that the magnetic properties are dominated by the static and dynamic electronic properties at the Co2 sites. We evidence that they display a strong in plane electronic anisotropy initially unexpected but which accords perfectly with an orbital ordering along the kagomé sublattice organization. These detailed data should now permit realistic calculations of the electronic properties of this compound in order to determine the incidence of electronic correlations.

20 pages, 15 figures, 3 tables, published in Phys. Rev. B, added new Appendix A

References in corpus (12)

• Fermi surface evolution and Luttinger theorem in Na${}_x$CoO${}_2$: a systematic photoemission study
• Evidence of a single nonmagnetic Co3+ state in the Na1CoO2 cobaltate
• Searching for Stable Na-ordered Phases in Single Crystal Samples of gamma-NaxCoO2
• Electronic texture of the thermoelectric oxide Na0.75CoO2
• Spin correlations and cobalt charge states: A new phase diagram of sodium cobaltates
• Na ordering imprints a metallic kagome lattice onto the Co planes of Na2/3CoO2
• Na atomic order, Co charge disproportionation and magnetism in Na${}_x$CoO${}_2$ for large Na contents
• Interplay between magnetic properties and thermoelectricity in misfit and Na cobaltates
• ^{59}Co NMR evidence for charge ordering below T_{CO}\sim 51 K in Na_{0.5}CoO_2
• Coulomb correlations do not fill the e'_g hole pockets in Na_{0.3}CoO_2
• Sodium Trimer Ordering on NaxCoO2 Surface
• The origin of a${}_{1g}$ and e${}_g$' orderings in Na${}_x$CoO${}_2$

Cited by in corpus (11)

• Hidden kagome-lattice picture and origin of high conductivity in delafossite PtCoO${}_2$
• Magnetic fluctuations and specific heat in NaxCoO2 near a Lifshitz topological transition
• Theoretical analysis of oxygen vacancies in layered sodium cobaltate Na_xCoO_{2-δ}
• Na order and Co charge disproportionation in Na${}_x$CoO${}_2$
• 23Na NMR study of sodium order in NaxCoO2 with 22K Neel temperature
• Evolution of Co charge disproportionation with Na order in Na${}_x$CoO${}_2$
• NMR in strongly correlated materials
• Interplay between strong correlations and electronic topology in the underlying kagome lattice of Na2/3CoO2
• Complex magnetic differentiation of cobalts in Na${}_x$CoO${}_2$ with 22K Néel temperature
• Ab-initio studying of spin states of sodium cobaltate Na${}_{2/3}$CoO${}_2$
• NMR study of the local magnetic order in the kagome Weyl semimetal Co${}_3$Sn${}_2$S${}_2$