Charge order, dielectric response and local structure of La5/3Sr1/3NiO4 system

TL;DR

This study investigates charge ordering, dielectric response, and local structural distortions in La5/3Sr1/3NiO4, revealing significant NiO2 plane distortions linked to high dielectric permittivity and ferroelectric-like transition.

Contribution

It provides combined X-ray scattering, dielectric, and EXAFS analysis showing local NiO2 distortions as key to dielectric properties and charge ordering in La5/3Sr1/3NiO4.

Findings

High dielectric permittivity (e=100 at 5K) observed.

Significant local distortions in NiO2 planes detected.

Charge ordering exhibits ferroelectric-like second order transition.

Abstract

Charge ordering, dielectric permittivity and local structure of La5/3Sr1/3NiO4 system have been explored X-ray charge scattering, complex dielectric impedance spectroscopy, and extended X-ray absorption fine structure (EXAFS) measurements, made on the same single crystal sample. The local structure measured by the temperature dependent polarized Ni K-edge EXAFS shows significant distortions in the NiO2 planes. These local distortions could be reasonable cause of high dielectric permittivity of the title system (e=100 at 5K) with the charge ordering in this system being a ferroelectric-like second order transition.