On the origin of unusual transport properties observed in densely packed polycrystalline CaAl_{2}

TL;DR

This paper investigates the unusual transport properties in densely packed polycrystalline CaAl_{2}, attributing them to polaron-mediated hopping processes consistent with the Shklovskii-Efros localization scenario, explaining the observed resistivity and thermopower behaviors.

Contribution

It proposes a novel explanation for the transport anomalies in CaAl_{2} based on localization and polaron hopping, aligning experimental features with theoretical models.

Findings

Resistivity follows a -3/4 power law with temperature.

Thermopower exhibits an N-like temperature dependence.

Transport behavior aligns with the Shklovskii-Efros localization scenario.

Abstract

A possible origin of unusual temperature behavior of transport coefficients observed in densely packed polycrystalline CaAl_{2} compound [M. Ausloos et al., J. Appl. Phys. 96, 7338 (2004)] is discussed, including a power-like dependence of resistivity with $\rho \propto T^{-3/4}$ and N-like form of the thermopower. All these features are found to be in good agreement with the Shklovskii-Efros localization scenario assuming polaron-mediated hopping processes controlled by the Debye energy.