Electrodynamics of Josephson vortex lattice in high-temperature superconductors

TL;DR

This paper investigates the high-frequency electrodynamics of Josephson vortex lattices in layered high-temperature superconductors, revealing how dissipation parameters influence plasma resonance features and comparing theoretical predictions with experimental observations.

Contribution

It provides a numerical analysis of the frequency-dependent response of Josephson vortex lattices, linking dissipation effects to observable plasma resonance phenomena in high-temperature superconductors.

Findings

Identification of the Josephson-plasma-resonance peak behavior under different dissipation regimes.

Discovery of additional satellite peaks in the loss function at high frequencies in dilute lattices.

Observation of a low-frequency peak caused by in-plane dissipation, matching experimental data.

Abstract

We studied response of the Josephson vortex lattice in layered superconductors to the high-frequency c-axis electric field. We found a simple relation connecting the dynamic dielectric constant with the perturbation of the superconducting phase, induced by oscillating electric field. Numerically solving equations for the oscillating phases, we computed the frequency dependences of the loss function at different magnetic fields, including regions of both dilute and dense Josephson vortex lattices. The overall behavior is mainly determined by the c-axis and in-plane dissipation parameters, which is inversely proportional to the anisotropy. The cases of weak and strong dissipation are realized in $\mathrm{Bi_{2}Sr_{2}CaCu_{2}O_{x}}$ and underdoped $\mathrm{YBa_{2}Cu_{3} O_{x}}$ correspondingly. The main feature of the response is the Josephson-plasma-resonance peak. In the weak-dissipation case additional satellites appear in the dilute regime mostly in the higher-frequency region due to excitation of the plasma modes with the wave vectors set by the lattice structure. In the dense-lattice limit the plasma peak moves to higher frequency and its intensity rapidly decreases, in agreement with experiment and analytical theory. Behavior of the loss function at low frequencies is well described by the phenomenological theory of vortex oscillations. In the case of very strong in-plane dissipation an additional peak in the loss function appears below the plasma frequency. Such peak has been observed experimentally in underdoped $\mathrm{YBa_{2}Cu_{3} O_{x}}$. It is caused by frequency dependence of in-plane contribution to losses rather then a definite mode of phase oscillations.