Abinitio evaluation of the local effective interactions in the superconducting compound Na0.35CoO2∙1.3H2O
Sylvain Landron, Marie-Bernadette Lepetit
DOI 10.1103/PhysRevB.74.184507 · Physical Review B
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Abstract
We used ab initio quantum chemical methods, treating explicitly the strong correlation effects within the cobalt 3d shell, as well as the screening effects on the effective integrals, for accurately determining on-site and nearest-neighbor (NN) interactions in the Na0.35CoO2∙1.3H2O superconducting compound. The effective ligand field splitting within the t2g orbitals was found to be δ∼300meV, the a1g orbital being destabilized compared to the eg′ ones. The effective Hund’s exchange and Coulomb repulsion were evaluated to JH∼280meV and U∼4.1–4.8eV for the a1g orbitals. The NN hopping parameters were determined within the three t2g orbitals and found to be of the same order of magnitude as the t2g ligand field splitting. This result supports the hypothesis that a three band model would be better suited than a one-band model for this system. Finally we evaluated the NN effective exchange integral to be antiferromagnetic and J=−66meV.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| Na0.35CoO2.1.3H2O Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |
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