Electronic theory for itinerant in-plane magnetic fluctuations in Na x CoO2

M. M. Korshunov, I. Eremin, A. Shorikov, V. I. Anisimov

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10 Citations (Scopus)

Abstract

Starting from the ab initio band structure for NaxCoO 2, we derive the single-electron energies and the effective tight-binding description for the t2g bands using a projection procedure. We find that, due to the presence of the next-nearest-neighbor hoppings, a local minimum in the electronic dispersion close to the Γ point of the first Brillouin zone forms. Therefore, in addition to a large Fermi surface, an electron pocket close to the Γ point emerges at high doping concentrations. The latter yields a new scattering channel resulting in the peak structure of the itinerant magnetic susceptibility at low momenta. This indicates an itinerant in-plane ferromagnetic state above a certain critical concentration xm , which is in agreement with neutron scattering data. Below xm , the magnetic susceptibility shows a tendency towards antiferromagnetic fluctuations. We estimate the value of 0.56 < x m < 0.68 within the rigid band model and within the Hubbard model with infinite on-site Coulomb repulsion consistent with the experimental phase diagram.

Original languageEnglish
Pages (from-to)650-655
Number of pages6
JournalJETP Letters
Volume84
Issue number12
DOIs
Publication statusPublished - Feb 2007
Externally publishedYes

Keywords

  • 31.15.Ar
  • 71.10.-w
  • 74.70.-b
  • 75.40.Cx

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