Plasma resonance and remaining Josephson coupling in the ``decoupled vortex liquid phase'' in layered superconductors

TL;DR

This paper investigates the plasma resonance in layered superconductors, showing it can persist without global coherence if the resonance frequency exceeds interlayer phase slip frequencies, and relates it to Josephson energy and experimental data.

Contribution

It establishes a connection between plasma resonance and Josephson coupling in a decoupled vortex liquid phase, using high temperature expansion and Monte Carlo simulations.

Findings

Resonance persists without global coherence if frequency exceeds phase slip frequency.

Plasma frequency relates to the average Josephson energy.

High temperature expansion matches experimental scaling.

Abstract

We relate the frequency of the plasma resonance in layered superconductors with the frequency dependent superconducting response along the c-direction. We demonstrate that the sharp resonance can persist even when the global superconducting coherence in this direction is absent provided the resonance frequency is larger than the typical frequency of interlayer phase slips. In this situation the plasma frequency is determined by the average Josephson energy, which can be calculated using the high temperature expansion. We also find the temperature dependence of the average Josephson energy from the Monte Carlo simulations of the uniformly frustrated XY model and determine the applicability region of the high temperature expansion. The field and temperature scaling of the plasma frequency suggested by the high temperature expansion is consistent with experiment.