Abstract
We report an inverse Raman-bleaching anomaly of oxygen-vacancy-activated phonons in underdoped excited in resonance at . These modes are closely related to modes that photobleach under visible excitation. The resonance and selection rules match the prediction from the in-plane anisotropy of the dielectric function, as does their growth of intensity under illumination. These properties support the oxygen-vacancy-reordering model for photoinduced changes in underdoped . We suggest that a similar coupling to anisotropic electronic resonances is responsible for the recently discovered anisotropies in the phonon dispersion.
- Received 27 September 2005
DOI:https://doi.org/10.1103/PhysRevB.74.024519
©2006 American Physical Society