Magnetic excitation spectra in single crystals of YBa2Cu306+;c with superconducting transition temperature Tc - 66 K (a:-0.75) and 90 K (x-0.9) are reported. For excitation energies in the range 25-45 meV, a scan at fixed energy yields a single peak with a large q-width centered on the antiferromagnetic wave vector, (n,n), in agreement with the work of Rossat-Mignod and coworkers. However, in contrast to the results of the latter group, we have not observed, despite significant effort, any (N-dependent magnetic scattering in either crystal at energies below ∼ 20 meV, even at temperatures far above Tc.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)