We develop the theory and application of small tip angle NMR techniques that can be used to measure couplings between nuclear spins and multiple neighboring spins. We employ the techniques to measure indirect (electron-mediated) nuclear spin-spin couplings between neighboring 63,65Cu and 17O nuclear spins in the high-temperature superconductor YBa2Cu3O7. Predictions for the values of these couplings can be obtained from the existing phenomenological models of electronic spin susceptibility x(q,ω) and hyperfine couplings that have been used in attempts to understand the wide body of YBa2Cu3O7 NMR data gathered to date. We find that the measured couplings are incompatible with these models.
|Number of pages
|Physical Review B - Condensed Matter and Materials Physics
|Published - 2001
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics