Charge effects and Josephson plasma resonance on planar defects in high-temperature superconductors

We show that planar crystalline defects parallel to the ab planes in high-T -c superconductors (HTS) give rise to a localized Josephson plasma mode for med by a collective Coulomb interaction of interlayer junctions. This resul ts in a pronounced satellite line in the real part of the complex resistivi ty R(omega), whose position and amplitude depend on the critical current de nsity J(0) and on the parameters of the charge interlayer coupling. The nar rowness of the zero-field plasma peak in ReR(omega) enables one to probe th e pairing symmetry of the interplane coupling by extracting the angular dep endence of J(0)(theta) across twist grain boundaries in HTS bicrystals.