Anomaly in the dielectric response at the charge orbital ordering transition of crystalline Pr0.67Ca0.33MnO3

TL;DR

This study investigates the dielectric response of Pr0.67Ca0.33MnO3 across a wide temperature range, revealing a significant peak at the charge ordering transition linked to phase separation phenomena.

Contribution

It provides new insights into the dielectric behavior at the charge ordering transition and its relation to phase separation in manganite crystals.

Findings

A strong dielectric peak up to two million at TCO

Evidence of phase separation between insulating and metallic states

Single Debye relaxation process observed

Abstract

The complex impedance of a Pr0.67Ca0.33MnO3 crystal has been measured. The frequency dependence is studied for a wide range of temperatures (50K-403K) and is found to be characteristic of relaxation process with a single Debye time relaxation constant, which is interpreted as a dielectric constant of the material. A strong peak is observed in this dielectric constant (up to two millions) at the charge ordering transition suggesting an interpretation in terms of ordering of electric dipoles at TCO or in term of phase separation. Comparison with Pr0.63Ca0.37MnO3 - in which the phase separation is much smaller and the peak in the dielectric constant is absent - suggests an interpretation in term of phase separation between insulating and metallic states.