Emergence of ferromagnetism and Jahn-Teller distortion in low Cr-substituted LaMnO3

TL;DR

This study investigates how low levels of Cr substitution in LaMnO3 induce ferromagnetism without reducing Jahn-Teller distortion, revealing complex orbital interactions.

Contribution

It demonstrates that ferromagnetism emerges in Cr-substituted LaMnO3 without weakening Jahn-Teller distortion, highlighting a different mechanism from hole doping.

Findings

Mn and Cr magnetic moments are proportional and follow macroscopic magnetization.

Cr and Mn ferromagnetic components are antiferromagnetically coupled.

Jahn-Teller distortion remains unchanged with Cr substitution up to x=0.15.

Abstract

The emergence of a ferromagnetic component in $LaMnO_{3}$ with low Cr-for-Mn substitution has been studied by x-ray absorption spectroscopy and x-ray magnetic circular dichroism at the Mn and Cr K edges. The local magnetic moment strength for the Mn and Cr are proportional to each other and follows the macroscopic magnetization. The net ferromagnetic components of $Cr^{3+}$ and $Mn^{3+}$ are found antiferromagnetically coupled. Unlike hole doping by La site substitution, the inclusion of $Cr^{3+}$ ions up to x = 0.15 does not decrease the Jahn-Teller (JT) distortion and consequently does not significantly affect the orbital ordering. This demonstrates that the emergence of the ferromagnetism is not related to JT weakening and likely arises from a complex orbital mixing.