C-AXIS MICROWAVE CONDUCTIVITY OF BI2SR2CACU2OY IN THE SUPERCONDUCTINGSTATE

Out-of-plane electrodynamic properties of nearly optimally doped Bi2Sr 2CaCu2Oy in the superconducting state have been studied at 14.2 GHz wi th the microwave electric field parallel to the c axis. The zero cross ing of the c-axis dielectric constant, which arises from the Josephson plasma resonance, was observed just below T-c. The c-axis microwave c onductivity sigma(1)(c)(T) was found to decrease rapidly just below T- c and remained suppressed even in the superconducting state. The resul ts suggest that the strong confinement of the excited carriers in the CuO2 planes is essentially retained even through the superconducting t ransition. [S0163-1829(98)10317-X].