On the Fermi Liquid to Polaron Crossover II: Double Exchange and the Physics of "Colossal" Magnetoresistance

TL;DR

This paper employs dynamical mean field theory to analyze a model capturing the key physics of colossal magnetoresistance manganites, focusing on electron-lattice interactions, magnetism, and transport properties.

Contribution

It introduces a comprehensive model combining Jahn-Teller coupling, classical oscillators, and ferromagnetic interactions to explain colossal magnetoresistance phenomena.

Findings

Identifies regimes of electron localization and delocalization.

Provides temperature and frequency-dependent conductivity data.

Shows qualitative agreement with experimental manganite data.

Abstract

We use the dynamical mean field method to study a model of electrons Jahn-Teller coupled to localized classical oscillators and ferromagnetically coupled to ``core spins'', which, we argue, contains the essential physics of the ``colossal magnetoresistance'' manganites $Re_{1-x} A_x MnO_3$. We determine the different regimes of the model and present results for the temperature and frequency dependence of the conductivity, the electron spectral function and the root mean square lattice parameter fluctuations. We compare our results to data, and give a qualitative discussion of important physics not included in the calculation. Extensive use is made of results from a companion paper titled: ``On the Fermi Liquid to Polaron Crossover I: General Results''.