Abstract
We report a state-of-the-art photoemission (angle-resolved photoemission spectroscopy) study of high quality single crystals of the NaxCoO2 series focusing on the fine details of the low-energy states. The Fermi velocity is found to be small (<0.5 eV Å) and only weakly anisotropic over the Fermi surface at all dopings, setting the size of the pair wave function to be on the order of 10-20 nm. In the low-doping regime, the exchange interlayer splitting vanishes and two-dimensional collective instabilities such as 120°-type fluctuations become kinematically allowed. Our results suggest that the unusually small Fermi velocity and the unique symmetry of kinematic instabilities distinguish cobaltates from most other oxide superconductors.
Original language | English (US) |
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Article number | 216405 |
Journal | Physical review letters |
Volume | 96 |
Issue number | 21 |
DOIs | |
State | Published - 2006 |
All Science Journal Classification (ASJC) codes
- General Physics and Astronomy