Interplay of superexchange and orbital degeneracy in Cr-doped LaMnO3

TL;DR

This study investigates how Cr-doping affects the structural, magnetic, and ESR properties of LaMnO3, revealing a transition from Jahn-Teller distorted to pseudocubic phases and changes in magnetic moments.

Contribution

It provides new insights into the interplay between superexchange interactions and orbital degeneracy in Cr-doped LaMnO3, highlighting structural and magnetic transitions.

Findings

Reduction of Jahn-Teller distortion with Cr-doping

Transition from orthorhombic to pseudocubic phase between x=0.3 and 0.4

Effective magnetic moments are reduced compared to spin-only values

Abstract

We report on structural, magnetic and Electron Spin Resonance (ESR) investigations in the manganite system LaMn_{1-x}Cr_{x}O_{3} (x<=0.5). Upon Cr-doping we observe a reduction of the Jahn-Teller distortion yielding less distorted orthorhombic structures. A transition from the Jahn-Teller distorted O' to the pseudocubic O phase occurs between 0.3<x<0.4. A clear connection between this transition and the doping dependence of the magnetic and ESR properties has been observed. The effective moments determined by ESR seem reduced with respect to the spin-only value of both Mn^{3+} and Cr^{3+} ions.