Resonant X-ray Study on the Bi-Layered Perovskite Mn Oxide LaSr2Mn2O7

TL;DR

This study investigates charge and orbital ordering in LaSr2Mn2O7 using resonant and non-resonant X-ray scattering, revealing temperature-dependent behaviors and phase coexistence in the material.

Contribution

It provides new insights into the temperature evolution and phase coexistence of charge and orbital orderings in a bi-layered manganite compound.

Findings

Charge and orbital orderings appear below 210 K.

Maximum ordering intensities occur at 160 K.

Charge and orbital ordered regions coexist within the antiferromagnetic phase.

Abstract

Charge and orbital ordering behaviors in the half doped bi-layered compound LaSr2Mn2O7 have been studied by resonant and non-resonant X-ray scattering. Three different order parameters, which correspond to the A-type antiferromagnetic, a charge and an orbital ordered states, were observed by measuring the magnetostriction and the superlattice peaks characterized by wavevectors (1/2 1/2 0) and (1/4 1/4 0), respectively. The superlattice reflections indicating the charge and orbital ordered states were observed below 210 K. Both the intensities reach a maximum at 160 K on cooling and become very weak below 100 K. The peak width of the charge ordered state agrees with that of the orbital ordered state at all temperatures studied. These results indicate that both the states originate from a single phase and that the charge/orbital ordered islands with definite interfaces disperse in the A-type antiferromagnetic phase. The dimensionality of the charge/orbital ordered phase is discussed using this model.