Publication details

Origin of strong correlations and superconductivity in NaxCoO2



Year of publication 2008
Type Article in Periodical
Magazine / Source Physical Review B
MU Faculty or unit

Faculty of Science

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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