Anisotropic ultraviolet Raman resonance in underdoped YBa2Cu3O6.7
Abstract
We report an inverse Raman-bleaching anomaly of oxygen-vacancy-activated phonons in underdoped YBa2Cu3O6.7 excited in resonance at 4.1eV . These modes are closely related to modes that photobleach under visible excitation. The resonance and selection rules match the prediction from the ab 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 YBa2Cu3O7-δ . We suggest that a similar coupling to anisotropic electronic resonances is responsible for the recently discovered ab anisotropies in the phonon dispersion.
- Publication:
-
Physical Review B
- Pub Date:
- July 2006
- DOI:
- 10.1103/PhysRevB.74.024519
- Bibcode:
- 2006PhRvB..74b4519B
- Keywords:
-
- 74.72.Bk;
- 74.25.Kc;
- 74.25.Jb;
- 78.30.-j;
- Y-based cuprates;
- Phonons;
- Electronic structure;
- Infrared and Raman spectra