UC Irvine

The Cu63 Knight shift in YBa2Cu3O7 has been measured at both Cu(1) (chain) and Cu(2) (plane) sites, using a uniaxially aligned powder. The isotropic part of the spin Knight shift (Ks) was found to be positive for both sites, suggesting large transferred hyperfine fields from oxygen p states. The Knight shifts at both sites show significant change below Tc, indicating important roles of both the planes and chains in the superconductivity. Despite the uncertainty in the diamagnetic screening, the axial part of Ks at Cu(2) sites is found to show linear-T behavior at low temperatures. © 1989 The American Physical Society.