Local structural changes in paramagnetic and charge ordered phases of Sm0.2Pr0.3Sr0.5MnO3: An EXAFS Study

TL;DR

This study investigates local structural changes in Sm0.2Pr0.3Sr0.5MnO3 across different magnetic and charge-ordered phases using EXAFS, revealing tilting of MnO6 octahedra and rare earth ion shifts as key factors.

Contribution

It provides detailed insights into the local structural modifications associated with different magnetic and charge-ordered phases in Sm0.2Pr0.3Sr0.5MnO3 using EXAFS analysis.

Findings

Tilting and rotation of MnO6 octahedra drive charge ordering.

Rare earth ion shifts influence bond distance distributions.

Structural changes correlate with magnetic phase transitions.

Abstract

Sm{0.5-x}Pr{x}Sr{0.5}MnO{3} exhibits variety of ground states as x is varied from 0 to 0.5. At an intermediate doping of x = 0.3 a charge-ordered CE type antiferromagnetic insulating (AFI) ground state is seen. The transition to this ground state is from a paramagnetic insulating (PMI) phase through a ferromagnetic metallic phase (FMM). Local structures in PMI and AFI phases of x = 0.3 sample have been investigated using Pr K-edge and Sm K-edge Extended X-ray Absorption Fine Structure (EXAFS). It can be seen that the tilting and rotation of the MnO6 octahedra about the b-axis are responsible for the charge ordered CE-type antiferromagnetic ground state at low temperatures. In addition a shift in the position of the rare earth ion along the c-axis has to be considered to account for observed distribution of bond distances around the rare earth ion.