Collective modes in multiband superfluids and superconductors: Multiple dynamical classes

TL;DR

This paper explores the collective excitation modes in multiband superconductors, revealing multiple Leggett modes with distinct masses that can classify the dynamical behavior of these systems.

Contribution

It introduces a classification of Leggett modes in three-band systems based on inter-band Josephson currents, offering a dynamic characterization of multiband superconductivity.

Findings

Multiple Leggett modes with different masses identified.

Classification into dynamical classes based on Josephson current interactions.

Provides a dynamic perspective on multiband superconductivity.

Abstract

One important way to characterize the states having a gauge symmetry spontaneously broken over multibands should be to look at their collective excitation modes. We find that a three-band system has multiple Leggett modes with significantly different masses, which can be classified into different dynamical classes according to whether multiple inter-band Josephson currents add or cancel. This provides a way to dynamically characterize multiband superconductivity while the pairing symmetry is a static property.