We have performed 17O NMR in YBa2Cu3O7 oriented powder samples in the temperature range 10-360 K for the orientation H0∥c and H0⊥c. The Electric Field Gradient (EFG) and Magnetic Hyperfine Shift (MHS) tensors have been determined for the four oxygen sites in the structure. The isotropic (axial) part of the MHS tensor were found to be equal to 0.21 (0.08)% for the O(2,3) site in the CuO2 plane and to 0.04(0.05)% for the bridging oxygen O(4). Both were found temperature independent in the normal state. Below Tc, they vanish to zero and the data for the MHS Kcc[O(2,3)] show that this decrease is faster than expected from BCS theory. The coupling between the localized spins at the Cu (2) sites and the mobile oxygen p-holes is discussed in the light of these results.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering