Josephson-plasma and vortex modes in layered superconductors

TL;DR

This paper theoretically investigates Josephson-plasma and vortex modes in layered superconductors, revealing their relation and explaining a recent magnetoabsorption resonance frequency jump as a phase transition between these modes.

Contribution

It provides a unified theoretical framework for understanding Josephson-plasma and vortex modes and their transition in layered superconductors.

Findings

Modes belong to the same lowest-frequency branch near vortices.

Resonance jump indicates a transition from Josephson-plasma to vortex mode.

Vortex line wandering enhances vortex mode mass.

Abstract

The Josephson-plasma and vortex modes in layered superconductors have been studied theoretically for low magnetic fields parallel and perpendicular to layers. The two modes belong to the same lowest-frequency branch of collective-mode spectrum localized near vortices. This is the Josephson-plasma resonance if pancakes are strongly pinned and cannot move. Otherwise the lowest-frequency mode is a vortex mode governed by pancake pinning and the vortex mass. The latter is strongly enhanced by wandering of a vortex line around its average direction. The recently observed jump of the magnetoabsorption-resonance frequency at the vortex phase transition line is interpreted as a transition from the Josephson-plasma to the vortex mode.