Josephson plasma and Josephson vortex lattice in high Tc superconductors with an applied magnetic field parallel to the layers

By use of the multi-Josephson junction model, we investigate Josephson plasma modes in the high T, superconductor with an applied magnetic field parallel to the layers. The capacitive and inductive effects are considered as inter-layer couplings. By numerical simulations, we obtain stable lattice structure of Josephson vortices, and calculate the spectrum of the Josephson plasma modes. It is shown that the triangular lattice of vortices is stable at high magnetic field, but it is distorted for H less than or equal to H-cr similar to Phi(0) / (2piD), where Phi(0) is the unit flux, lambda the penetration depth along the ab-plane and D the depth of the insulating layer. We identify two observable Josephson plasma modes; the higher mode increases with H, while the lower mode takes the maximum at H = H-cr and decreases with increasing H. (C) 2004 Elsevier B.V. All rights reserved.