Polaron relaxation and hopping conductivity in LaMn$_{1-x}$Fe$_{x}$O$_3$

TL;DR

This study investigates the charge transport mechanisms in LaMn$_{1-x}$Fe$_{x}$O$_3$, revealing polaronic behavior, variable range hopping, and Anderson localization effects across different compositions and temperatures.

Contribution

It provides new insights into how Fe substitution affects polaron relaxation and hopping conductivity in LaMnO$_3$-based materials.

Findings

Resistivity follows variable range hopping at low T and Arrhenius at high T.

AC conductivity exhibits power law behavior influenced by Anderson localization.

Charge transport dynamics are composition-dependent and temperature-independent for specific samples.

Abstract

Dc and ac transport properties as well as electric modulus spectra have been investigated for the samples LaMn$_{1-x}$Fe$_{x}$O$_3$ with compositions 0 $\leq x \leq$ 1.0. The bulk dc resistivity shows a temperature variation consistent with the variable range hopping mechanism at low temperature and Arrhenius mechanism at high temperatures. The ac conductivity has been found to follow a power law behavior at a limited temperature and frequency region where Anderson-localization plays a significant role in the transport mechanism for all the compositions. At low temperatures large dc resistivities and dielectric relaxation behavior for all the compositions are consistent with the polaronic nature of the charge carriers. Scaling of the modulus spectra shows that the charge transport dynamics is independent of temperature for a particular composition but depends strongly on different compositions possibly due to different charge carrier concentrations and structural properties.