Pseudogap Formation in Models for Manganites

TL;DR

This study uses Monte Carlo simulations to analyze the density-of-states and spectral functions in manganite models, revealing robust pseudogap features linked to phase separation and ferromagnetic clusters, consistent with experimental observations.

Contribution

It demonstrates that pseudogap formation is a generic feature of mixed-phase regimes in manganites, supported by detailed computational analysis.

Findings

Robust pseudogap features observed at low and intermediate temperatures.

Pseudogap follows the chemical potential and is caused by ferromagnetic cluster formation.

Results agree with recent photoemission experiments on manganites.

Abstract

The density-of-states (DOS) and one-particle spectral function $\rm A({\bf k}, \omega)$ of the one- and two-orbital models for manganites, the latter with Jahn-Teller phonons, are evaluated using Monte Carlo techniques. Unexpectedly robust pseudogap (PG) features were found at low- and intermediate-temperatures, particularly at or near regimes where phase-separation occurs as $\rm T$$\to$0. The PG follows the chemical potential and it is caused by the formation of ferromagnetic metallic clusters in an insulating background. It is argued that PG formation should be generic of mixed-phase regimes. The results are in good agreement with recent photoemission experiments for $\rm La_{1.2} Sr_{1.8} Mn_2 O_7$.