Indications of coherence-incoherence crossover in layered transport

TL;DR

This paper investigates the crossover from coherent to incoherent interlayer transport in layered metals using a small polaron model, analyzing spectral functions, optical conductivity, and magnetoresistance.

Contribution

It introduces a concrete small polaron model to explain the temperature-dependent transition between coherent and incoherent interlayer transport in layered metals.

Findings

Spectral function shows a transition from coherent to incoherent behavior with temperature.

Interlayer optical conductivity has distinct coherent and incoherent contributions.

Interlayer magnetoresistance exhibits signatures of the coherence-incoherence crossover.

Abstract

For many layered metals the temperature dependence of the interlayer resistance has a different behavior than the intralayer resistance. In order to better understand interlayer transport we consider a concrete model which exhibits this behavior. A small polaron model is used to illustrate how the interlayer transport is related to the coherence of quasi-particles within the layers. Explicit results are given for the electron spectral function, interlayer optical conductivity and the interlayer magnetoresistance. All these quantities have two contributions: one coherent (dominant at low temperatures) and one incoherent (dominant at high temperatures).