Ferromagnetic transition in the double-exchange model on the pyrochlore lattice

TL;DR

This study numerically investigates the ferromagnetic transition in the double-exchange model on a frustrated pyrochlore lattice, highlighting the effectiveness of twisted boundary conditions in finite-size Monte Carlo simulations.

Contribution

It introduces a method using twisted boundary conditions to accurately estimate transition temperatures in frustrated lattice models.

Findings

Finite-size corrections are reduced with twisted boundary conditions.

Estimated transition temperatures are compared between pyrochlore and cubic lattices.

Abstract

The double-exchange model, which has been extensively studied in the context of colossal magneto-resistance in perovskite manganese oxides, is known to exhibit a ferromagnetic metallic state at low temperatures because of the interplay between localized moments and itinerant electrons through the Hund's-rule coupling. Here we investigate numerically the ferromagnetic transition in the double-exchange model defined on the frustrated pyrochlore lattice as a simple model for ferromagnetic pyrochlore oxides. We demonstrate that the finite-size corrections are largely reduced by implementing averages over the twisted boundary conditions in the Monte Carlo simulation, which enables to estimate the ferromagnetic transition temperature in relatively small size clusters. The estimate is compared with that for the non-frustrated cubic lattice system.