TIME-DEPENDENT EQUATIONS FOR PHASE DIFFERENCES AND A COLLECTIVE MODE IN JOSEPHSON-COUPLED LAYERED SUPERCONDUCTORS

A time-dependent equation for the interlayer phase differences is deri ved for Josephson-coupled layered superconductors. It generalizes the sine-Gordon equation for the phase in a standard Josephson junction to the case of multilayer systems. With the help of this equation, the d ispersion of a collective mode is found at low temperatures. In highly anisotropic systems the gap in the spectrum of this mode lies below t he superconducting gap and is suppressed strongly by a magnetic field parallel to the layers. The effect of this mode on the dielectric func tion and specific heat is calculated.