Normal state of short coherence length superconductors: Qualitative differences between spin and charge correlations
The temperature scaleT* at which the amplitude of the order parameter is formed is in general much higher than theT c 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 rangeT c <T<T*. We find thatχ s 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∼χ s (T) characteristic of spin gap behavior in the high-T c materials.
Key wordsShort coherence length superconductor attractive Hubbard model normal-state anomalies Non-Fermi liquid
Unable to display preview. Download preview PDF.
- 1.M. Randeria, N. Trivedi, A. Moreo, and R. T. Scalettar,Phys. Rev. Lett. 69, 2001 (1992).Google Scholar
- 2.N. Trivedi and M. Randeria (preprint).Google Scholar
- 3.R. T. Scalettaret al., Phys. Rev. Lett. 62, 1407 (1989); A. Moreo and D. J. Scalapino,Phys. Rev. Lett. 66, 946 (1991).Google Scholar
- 4.C. Sa de Melo, M. Randeria, and J. R. Engelbrecht,Phys. Rev. Lett. 71, 3202 (1993). For a detailed review and references on the BCS-Bose crossover, see M. Randeria, inBose-Einstein Condensation, edited by A. Griffin, D. Snoke, and S. Stringari (Cambridge University Press, 1995).Google Scholar
- 5.W. W. Warrenet al., Phys. Rev. Lett. 62, 1193 (1989); M. Takigawaet al., Phys. Rev. B 43, 247 (1991); H. Alloulet al., Phys. Rev. Lett. 70, 1171 (1993); R. E. Walstedtet al., Phys. Rev. Lett. 72, 3610 (1994).Google Scholar