Origin of strong correlations and superconductivity in NaxCoO2
| Authors | |
|---|---|
| Year of publication | 2008 |
| Type | Article in Periodical |
| Magazine / Source | Physical Review B |
| MU Faculty or unit | |
| Citation | |
| Doi | http://dx.doi.org/10.1103/PhysRevB.77.104532 |
| Field | Solid matter physics and magnetism |
| Keywords | layered cobaltates; strong correlations; superconductivity |
| Description | We propose a minimal model resolving a puzzle of enigmatic correlations observed in sodium-rich NaxCoO2 where one expects a simple, free motion of the dilute S = 1 / 2 holes doped into a band insulator NaCoO2. The model also predicts singlet superconductivity at experimentally observed compositions. The model is based on a key property of cobalt oxides - the spin-state quasidegeneracy of CoO6 octahedral complex -leading to an unusual physics of, e.g., LaCoO3. We show that correlated hopping between t2g and eg states leads to the spin-polaron physics at x~1, and to an extended s-wave pairing at larger doping when coherent fermionic bands are formed. |
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