t-Jmodel and nuclear magnetic relaxation in high-Tcmaterials

Abstract

We obtain the Fermi contact term of the electron-nuclear effective Hamiltonian describing the coupling between the planar Cu(2) nucleus and the O(2,3) nuclei on the one hand, and the effective degrees of freedom of the one band t-J (or Heisenberg Hubbard) model on the other. The details of the resulting couplings suggest that the copper and oxygen relaxation rates are sensitive to antiferromagnetic correlations in different degree. In the insulating phase we predict that the effective dynamical critical exponent for O(2,3) is reduced by two from that of Cu(2).