Metallic ferromagnetism-insulating charge order transition in doped manganites

TL;DR

This paper investigates how the interplay of double exchange and impurity randomness influences the competition between metallic ferromagnetic and insulating charge-ordered states in doped manganites, revealing a transition between these phases.

Contribution

It introduces a combined model using dynamical mean-field theory to explain charge order and ferromagnetism competition in doped manganites, incorporating impurity effects and simplified double exchange.

Findings

Checkerboard charge order can exist within the ferromagnetic phase at low temperatures.

An insulator-metal transition occurs at the charge order-ferromagnetic phase boundary.

The model provides explicit expressions for transport properties in terms of spectral functions.

Abstract

We show that an interplay of double exchange and impurity randomness can explain the competition between metal-ferromagnetic and insulating charge ordered states in doped manganites. The double exchange is simplified in the Ising type, whereas the randomness is modeled by the Falicov-Kimball binary distribution. The combined model is considered in a framework of dynamical mean-field theory. Using the Kubo-Greenwood formalism, the transport coefficients are explicitly expressed in terms of single particle spectral functions. Dividing the system into two sublattices we have pointed out a direct calculation to the checkerboard charge order parameter and the magnetizations. Numerical results show us that the checkerboard charge order can settle inside the ferromagnetic state at low temperature. An insulator-metal transition is also found at the point of the checkerboard charge order-ferromagnetic transition.