Plasma resonance in anisotropic layeredhigh−Tcsuperconductors

Abstract

The plasma resonance is described theoretically by the inductive coupling model for a large stacked Josephson-junction system such as the intrinsic Josephson-junction array in anisotropic $\mathrm{high}{\ensuremath{-}T}_{c}$ superconductors. Eigenmodes of the plasma oscillation are analytically described and a numerical example for the large stack case $N=50$ is given. The scaling length characteristic of each mode is discussed. Numerical results for the plasma resonance for $N=50$ in the presence of an external rf drive with wave number k are given. For k different from zero possible resonance modes among the eigen oscillation modes are shown, and it is further demonstrated that for $k=0$ the resonance takes place as a collection of N independent resonant Josephson junctions. Some guidelines for possible experiments are shown. It is also shown that very recent microwave experiments for the plasma resonance can be explained by this theory based on the inductive coupling, and collective longitudinal plasma oscillations are discussed.