Abstract
We have mapped the neutron scattering spin spectrum at low energies in , where the doping is near the critical value for superconductivity. No coexistence with long-range-ordered antiferromagnetism is found. The spins fluctuate on two energy scales: one a damped spin response with a relaxation rate and the other a central mode with a relaxation rate that slows to less than below . The spectrum mirrors that of a soft mode driving a central mode. Extremely short correlation lengths, in-plane and along the direction, and isotropic spin orientations for the central mode indicate that the correlations are subcritical with respect to any second-order transition to Néel order. The dynamics follows a model where damped spin fluctuations are coupled to the slow fluctuations of regions with correlations shortened by the hole doping.
- Received 13 January 2006
DOI:https://doi.org/10.1103/PhysRevB.73.100504
©2006 American Physical Society