Electronic and structural transition in $La_{0.2} Sr_{0.8} Mn O_3$

TL;DR

This study explores the coupled electronic and structural phase transition in La$_{0.2}$Sr$_{0.8}$MnO$_{3}$, revealing a first-order transition at 265 K with significant orbital and lattice distortions.

Contribution

It provides new insights into the interplay of electronic and structural changes, highlighting the role of MnO$_6$ distortions and orbital fluctuations in this material.

Findings

First-order phase transition at 265 K observed.

Distortions in MnO$_6$ octahedra persist in the cubic phase.

Orbital fluctuations influence electronic properties.

Abstract

We investigate the interplay of the electronic and structural transition in La$_{0.2}$Sr$_{0.8}$MnO$_{3}$. The transport and specific heat measurements exhibit unusual evolutions and signature of a first order phase transition around 265 K. Mn K-edge extended $x$-ray absorption fine structure results reveal distortion in the MnO$_6$ octahedra even in the cubic phase and a remarkable evolution of the distortion across the phase transition. These results manifest the importance of fluctuations in Mn 3$d$ orbital occupancy and disorder in their electronic properties, which may help in understanding the orbital and spin ordering proposed in these systems.