Influence of lattice distortion on the Curie temperature and spin-phonon coupling in LaMn$_{0.5}$Co$_{0.5}$O$_{3}$

TL;DR

This study explores how lattice distortions influence the magnetic transition temperature and spin-phonon interactions in LaMn$_{0.5}$Co$_{0.5}$O$_{3}$, revealing structural and magnetic differences between two ferromagnetic phases.

Contribution

It provides new insights into the relationship between lattice distortions, B-site ordering, and magnetic properties in LaMn$_{0.5}$Co$_{0.5}$O$_{3}$ using neutron diffraction and Raman spectroscopy.

Findings

Different ferromagnetic phases have distinct T_c values.

Structural distortions affect exchange interactions and T_c.

Spin-phonon coupling is observed around T_c in both phases.

Abstract

Two distinct ferromagnetic phases of LaMn$_{0.5}$Co$_{0.5}$O$_{3}$ having monoclinic structure with distinct physical properties have been studied. The ferromagnetic ordering temperature $\textit{T}_{c}$ is found to be different for both the phases. The origin of such contrasting characteristics is assigned to the changes in the distance(s) and angle(s) between Mn - O - Co resulting from distortions observed from neutron diffraction studies. Investigations on the temperature dependent Raman spectroscopy provide evidence for such structural characteristics, which affects the exchange interaction. The difference in B-site ordering which is evident from the neutron diffraction is also responsible for the difference in $\textit{T}_{c}$. Raman scattering suggests the presence of spin-phonon coupling for both the phases around the $\textit{T}_{c}$. Electrical transport properties of both the phases have been investigated based on the lattice distortion.