Non-Gaussian resistance noise in the ferromagnetic insulating state of a hole doped manganite

TL;DR

This paper reports large non-Gaussian 1/f resistance noise in the ferromagnetic insulating state of a hole-doped manganite, revealing charge fluctuations in a glassy polaronic phase.

Contribution

It demonstrates the presence of non-Gaussian resistance noise and links it to charge fluctuations in a correlated glassy phase in a manganite system.

Findings

Large 1/f noise observed in FMI state

Noise becomes non-Gaussian in FMI state

Noise magnitude sharply freezes out with cooling

Abstract

We report the observation of a large 1/f noise in the ferromagnetic insulating state (FMI) of a hole doped manganite single crystal of La0.80Ca0.20MnO3 which manifests hopping conductivity in presence of a Coulomb gap. The temperature dependent noise magnitude shows a deep within the FMI state, there is a sharp freeze out of the noise magnitude with temperature on cooling. As the material enters the FMI state, the noise becomes non-Gaussian as seen through probability density function and second spectra. It is proposed to arise from charge fluctuations in a correlated glassy phase of the polaronic carriers which develop in these systems as reported in recent simulation studies.