Dynamical Mean-Field Study of the Ferromagnetic Transition Temperature of a Two-Band Model for Colossal Magnetoresistance Materials

TL;DR

This study uses dynamical mean-field theory to analyze the ferromagnetic transition temperature in a two-band model for colossal magnetoresistance materials, revealing significant effects of band overlap and interband hopping on Tc.

Contribution

It demonstrates the importance of multiband effects and interband hopping in increasing the ferromagnetic transition temperature in double-exchange models.

Findings

Tc is much larger with band overlap compared to one-band models.

Nonzero interband hopping significantly increases Tc.

Results agree well with Monte Carlo simulations.

Abstract

The ferromagnetic (FM) transition temperature (Tc) of a two-band Double-Exchange (DE) model for colossal magnetoresistance (CMR) materials is studied using dynamical mean-field theory (DMFT), in wide ranges of coupling constants, hopping parameters, and carrier densities. The results are shown to be in excellent agreement with Monte Carlo simulations. When the bands overlap, the value of Tc is found to be much larger than in the one-band case, for all values of the chemical potential within the energy overlap interval. A nonzero interband hopping produces an additional substantial increase of Tc, showing the importance of these nondiagonal terms, and the concomitant use of multiband models, to boost up the critical temperatures in DE-based theories.