JOSEPHSON PLASMA EXCITATION IN HIGH-T-C SUPERCONDUCTORS WITH FINITE DIMENSIONS

The power absorption for a crystal with finite dimensions is calculate d when the microwave H-ac is applied parallel to the ab-plane. The scr eening current across the ab-planes induced by H-ac excites the transv erse Josephson plasma. The calculated absorption spectrum depends sens itively on the dimensions of the ab-plane L due to the interference of the Josephson plasma waves. For L less than a critical dimension L, which is comparable to the microwave wavelength in the superconductor, there is no absorption peak in the spectrum. For L> L, the spectrum exhibits distinct resonance peaks whose number increases successively with increasing L. The L-dependence of the spectra is confirmed by the recent microwave experiments made on various size of Bi2Sr2CaCu2O8+de lta crystals. (C) 1997 Elsevier Science B.V.