Abstract
Inelastic neutron scattering measurements on single crystals of superconducting reveal a magnetic excitation located at wave vectors () in tetragonal notation. On cooling below , a clear resonance peak is observed at this wave vector with an energy of 8.6(0.5) meV, corresponding to 4.5(0.3) . This is in good agreement with the canonical value of 5 observed in the cuprates. The spectrum shows strong dispersion in the tetragonal plane but very weak dispersion along the axis, indicating that the magnetic fluctuations are two dimensional in nature. This is in sharp contrast to the anisotropic three dimensional spin excitations seen in the undoped parent compounds.
- Received 28 November 2008
DOI:https://doi.org/10.1103/PhysRevLett.102.107005
©2009 American Physical Society