DEVIATIONS FROM FERMI-LIQUID BEHAVIOR ABOVE T-C IN 2D SHORT COHERENCE LENGTH SUPERCONDUCTORS

We show that there are qualitative differences between the temperature dependence of the spin and charge correlations in the normal state of the 2D attractive Hubbard model using quantum Monte Carlo simulations. The one-particle density of states shows a pseudogap above Tc with a depleted N0 with decreasing T. The susceptibility χs and the low frequency spin spectral weight track N0, which explains the spin-gap scaling: 1/T1T∼χsT. However, collective excitations contribute to the charge channel, and the compressibility dn/dμ is T independent. This anomalous "spin-charge separation" is shown to exist even at intermediate |U| where the momentum distribution nk gives evidence for a degenerate Fermi system. © 1995 The American Physical Society.