Abstract
The -axis reflectivity spectrum of underdoped (YBCO) is measured below in parallel magnetic fields up to 7 T. Upon application of a parallel field, a new peak appears at finite frequency in the optical conductivity at the expense of suppression of -axis condensate weight. We conclude that the dramatic change originates from different Josephson coupling strengths between bilayers with and without Josephson vortices. We find that the broad conductivity peak in YBCO gains the spectral weight under parallel magnetic field; this indicates that the condensate weight at is distributed to this peak as well as to the new optical Josephson mode.
- Received 29 April 2002
DOI:https://doi.org/10.1103/PhysRevLett.89.247001
©2002 American Physical Society