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The essential framework for cuprate superconductivity is that of a spin-1/2 electron system in the vicinity of a half filled (Mott) lattice. Of all oxide superconductors this framework is most closely matched in the sodium doped cobalt oxides except that it is realized on a triangular lattice. Besides superconductivity, the system exhibits spin-thermopower, metal-insulator transition, charge-order and antiferromagnetism. We have employed state-of-the-art ARPES to study the topology of the Fermi surface, quasiparticle renormalization, self-energy and its temperature evolution in most of these novel phases of cobaltates which provide the basic foundation for the low-energy electronic structure of cobaltates [1-5]. In this talk, I plan to report recent results on the superconductor, the correlated insulator and the high thermopower phase.
Reference: [1] M.Z. Hasan et.al., Phys. Rev. Lett. 92, 286402 (2004). [2] D. Qian et.al., Phys. Rev. Lett. 96, 216405 (2006). [3] D. Qian et.al., Phys. Rev. Lett. 96, 046407 (2006). [4] D. Qian et.al., Phys. Rev. Lett. 97, 186405 (2006). [5] M.Z. Hasan et.al., Annals of Physics 321, 1568 (2006). |
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