THEORY OF NUCLEAR SPIN-SPIN COUPLING IN YBA2CU3O7-DELTA

The indirect nuclear spin-spin coupling between Cu nuclei in the CuO2 planes of YBa2Cu3O7-sigma, deduced from Cu-63 transverse relaxation, is shown to yield information about the wave-vector dependence of the real part of the planar-Cu static electron-spin susceptibility. The coupling is evaluated with no adjustable parameters using the antiferromagnetic Fermi-liquid theory of Millis, Monien, and Pines, providing a new test of that model. At 100 K, the theoretical relaxation time is 190 +/- 75-mu-sec versus the experimental 130 +/- 10-mu-sec.