Impedance spectroscopy and conduction mechanism of a BiFe$_{0.95}$Mn$_{0.05}$O$_3$ thin film

TL;DR

This study investigates the dielectric response and conduction mechanisms of a BiFe$_{0.95}$Mn$_{0.05}$O$_3$ thin film, revealing interface and bulk contributions, polaronic hopping, and Schottky barrier effects.

Contribution

It provides a detailed analysis of the conduction mechanisms and dielectric behavior in Mn-doped BiFeO$_3$ thin films, linking impedance spectroscopy with conduction models.

Findings

Interface relaxation suggests Maxwell-Wagner space charge effects.

Polaronic hopping governs AC conductivity.

Schottky barrier influences DC conduction with 0.36 eV activation energy.

Abstract

Dielectric response and conduction mechanism were investigated for a multiferroic BiFe$_{0.95}$Mn$_{0.05}$O$_3$ epitaxial thin film. A contribution from a thermally activated interface (0.37 eV) and the bulk of the film on the dielectric response were observed through the comparison between experimental results and equivalent circuit model. The low frequency interface relaxation signatures strongly suggest a Maxwell-Wagner space charge origin. The alternative current conductivity deduced from the model follows a power law frequency dependence suggesting a polaronic hopping mechanism while the low frequency limit is in perfect agreement with the direct current conduction mechanism. The current-voltage characteristics were indeed correlated with Schottky-Simmons interface limited transport with activation energy of 0.36 eV, close to the one extracted from the impedance analysis. Such analysis of the electrostatic landscape and dielectric behaviour may help to further understanding the anomalous photo-induced properties in the BiFeO$_3$ system.