Superlinear dependence of the conductivity, double/single Jonscher variations and the contribution of various conduction mechanisms in transport properties of La0.5Ca0.2Ag0.3MnO3 manganite

Abstract

From the XRD results, it is found that the studied La0.5Ca0.2Ag0.3MnO3 compound crystallizes in the orthorhombic structure with Pnma space group. Electrical conductivity of La0.5Ca0.2Ag0.3MnO3 compound is investigated from 80 K to 480 K in the frequency range [40 Hz-6 × 105 Hz]. Several conduction models are used to identify the appropriate mechanisms governing the transport properties in the studied compound. The Overlapping-Large- Polaron Tunneling and the Correlated Barrier Hopping conduction processes are used to clarify the sub-linear dispersive regions in the DJPL/JPL frequency range. In these regions, the conductivity is examined according to double and single Jonscher power laws. At lower temperatures and for the second frequency range, the spectra reveal Superlinear Power-Law behavior. Beyond T = 280 K, this phenomenon is disappeared and replaced by Nearly Constant Loss behavior. At higher frequencies, the conductivity spectra exhibit a high frequency plateau. For the DC regime, the transport properties are governed by thermally activated Small Polaron Hopping conduction process at elevated temperatures. The Variable Range Hopping conduction mechanism is the dominant process in the intermediate temperature range. Thus, the cationic disorder plays a major role in the transport of charge carriers at low temperatures. Likewise, the investigated compound exhibits semi-conductor behavior over the explored temperature region. The deduced hopping energy is sensitive to the frequency parameter. At high frequencies, a signature of a metal-semiconductor transition is observed at 260 K. The magnetic investigation shows that the sample reveals a paramagnetic-ferromagnetic phase transition at 260 K.