Higher grade hybrid model of layered superconductors

TL;DR

This paper develops a hybrid layered superconductor model incorporating arbitrary-range Josephson couplings, analyzing gauge invariance, stability, and the impact of higher-order couplings on superconductivity enhancement.

Contribution

It introduces a novel hybrid discrete-continuous model for layered superconductors with arbitrary Josephson coupling range, extending existing models and exploring conditions for various superconducting states.

Findings

Higher order Josephson couplings can enhance superconductivity.

The model reduces to the Lawrence-Doniach model under specific conditions.

Conditions for alternating solutions and continuum descriptions are identified.

Abstract

A hybrid discrete-continuous model of layered superconductors with interlayer Josephson couplings of arbitrary range is constructed. The conditions required by gauge invariance and thermodynamical stability of the model are determined. Some important special cases, in particular transition to the classic Lawrence-Doniach model, are discussed. The conditions for presence of alternating solutions and the posibilities to describe such states of a superconductor by the continuum or bi-continuum models are examined. The enhancement of superconductivity caused by the presence of higher order Josephson couplings is shown.