HG-199 KNIGHT-SHIFT AND SPIN-LATTICE RELAXATION IN HGBA2 CUO4+DELTA

Hg-199 NMR spectra and T1(-1) are reported for two samples of HgBa2CuO 4+delta with superconducting transitions at T(c) = 95 K and T(c) = 80 K, respectively. The spectra are characteristic powder patterns with l arge anisotropic shifts: 3K(ax) = - 0.43% and -0.52%, respectively, fo r the two samples at room temperature with negligible temperature depe ndence below T(c). The isotropic Knight shifts were of order K(iso) = +0.11% with respect to a Hg(NO3)2 aqueous solution. The relaxation rat e is Korringa-like above T(c) while below T(c) the relaxation rate dro ps down exponentially without enhancement near T(c).