Suppression of ferromagnetic ordering in doped manganites: Effects of the superexchange interaction

TL;DR

This study uses Monte Carlo simulations to show how increasing antiferromagnetic superexchange interaction suppresses ferromagnetic order and lowers the transition temperature in doped manganites, linking superexchange strength to magnetic properties.

Contribution

It demonstrates the impact of superexchange interaction on ferromagnetic suppression in doped manganites through computational modeling, highlighting a potential mechanism for observed experimental phenomena.

Findings

Ferromagnetic transition temperature decreases with increasing superexchange interaction.

Suppression of ferromagnetism scales with bandwidth narrowing due to antiferromagnetic frustration.

Superexchange interaction influences magnetic ordering in doped manganites.

Abstract

From a Monte Carlo study of the ferromagnetic Kondo lattice model for doped manganites, including the antiferromagnetic superexchange interaction ($J_{AF}$), we found that the ferromagnetic ordering was suppressed as $J_{AF}$ increased. The ferromagnetic transition temperature $T_c$, as obtained from a mean field fit to the calculated susceptibilities, was found to decrease monotonically with increasing $J_{AF}$. Further, the suppression in $T_c$ scales with the bandwidth narrowing induced by the antiferromagnetic frustration originating from $J_{AF}$. From these results, we propose that the change in the superexchange interaction strength between the $t_{2g}$ electrons of the Mn ions is one of the mechanisms responsible for the suppression in $T_c$ observed in manganites of the type (La$_{0.7-y}$Pr$_{y}$)Ca$_{0.3}$MnO$_3$.