Normal state of short coherence length superconductors: Qualitative differences between spin and charge correlations
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The temperature scaleT* at which the amplitude of the order parameter is formed is in general much higher than theTc at which phase coherence is established in short coherence length superconductors. Using quantum Monte Carlo simulations for the attractive Hubbard model we show that for a degenerate 2D system the spin and charge responses show qualitatively different behavior in the normal state in the temperature rangeTc<T<T*. We find thatχs is stronglyT-dependent whiledn/dμ is independent ofT. A pseudo-gap develops in the one-particle density of states and leads to anomalous behavior of the NMR relaxation rate 1/T1T∼χs(T) characteristic of spin gap behavior in the high-Tc materials.
Key wordsShort coherence length superconductor attractive Hubbard model normal-state anomalies Non-Fermi liquid
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