EXPERIMENTAL TEST OF THE INTERLAYER PAIRING MODELS FOR HIGH-T-C SUPERCONDUCTIVITY USING GRAZING-INCIDENCE INFRARED REFLECTOMETRY

From measurements of the far-infrared reflectivity at grazing angles o f incidence with p-polarized light we determined the c-axis Josephson plasma frequencies of the single layer high-T-c cuprates Tl2Ba2CuO6 an d La2-xSrxCuO4. We detected a strong plasma resonance at 50 cm(-1) for La2-xSrxCuO4 in excellent agreement with previously published results . For Tl2Ba2CuO6 we were able to determine an upper limit of the unscr eened c-axis Josephson plasma frequency 100 cm(-1) or a c-axis penetra tion depth >15 mu m. The small value of omega(J) stands in contrast to recent a prediction based on the interlayer tunneling mechanism of su perconductivity.