The role of intermediate layers in the c-axis conductivity of layered superconductors

TL;DR

This paper presents a simplified model explaining the c-axis transport properties in high-temperature superconductors, linking the pseudogap phenomenon to layered band structure and interlayer coupling.

Contribution

It introduces an analytic, unified model for c-axis optical conductivity, resistivity, and penetration depth based on three key parameters, clarifying pseudogap origins.

Findings

Pseudogap arises naturally from layered band structure.

Analytic expressions for conductivity and penetration depth are derived.

Model provides a unified understanding of c-axis properties in high T_c cuprates.

Abstract

A simplified model of c axis transport in the high T_c superconductors is presented. Expressions are found for the c axis optical conductivity, the d.c. resistivity, and the c axis penetration depth. Within the framework of this model, the pseudogap in the optical conductivity arises naturally as a result of the layered band structure of the high T_c materials. We discuss the occurence of the pseudogap in terms of three parameters: a band gap Delta_{ps}, a temperature dependent scattering rate Gamma(T), and the strength of the interlayer coupling t_{perp}. We are also able to find analytic expressions for the d.c. conductivity and the low temperature penetration depth in terms of these three parameters. This work is an attempt to present a simple, unified picture of c axis properties in the high T_c cuprates.