A triple-axis neutron-scattering study has been done of the magnetic correlations in three large single crystals of YBa2Cu3O6+x with x=0.5, 0.8, and 0.9 having Tcs of 50, 60, and 80 K, respectively. The frequency dependence of the cross section at Q=(1/2,1/2,l) was found to peak near 5 meV for x=0.45 in an earlier study. Our data confirm that this peak shifts to 30 meV for x=0.5. Moreover, the low-frequency (<40 meV) spectra for x=0.8 and 0.9 become progressively suppressed with respect to those of the less oxygenated samples. These data are consistent with a picture in which the spectral weight of the magnetic scattering shifts to higher energy as the oxygen concentration x and carrier density increase.
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics