Electrical transport mechanism of manganite-based trilayer heterostructures in the Cusp and insulating regions

Abstract

In the present study, efforts are made to study the temperature dependent resistivity (ρ-T) variations of manganites (La0.7Sr0.3MnO3 (LSMO) single layer) and manganites-based systems ((LSMO/γ-Fe2O3/LSMO) trilayer heterostructures) in two distinct regions (Cusp region and Insulating region). Cusp region is an intermediate region between Metallic region and Insulating region. The resistivity-temperature curves are studied and analysed by various resistive models and fitting equations. The co-existence of ferromagnetic clusters and polarons manifests in the Cusp region. The Insulating region is explored and fitted under two regimes: Low Temperature Insulating region and High Temperature Insulating region. Various mathematical models viz. Thermal Activation model, Small Polaron Hopping model and Variable Range Hopping model were employed to study the ρ-T variations under various temperature ranges for LSMO (60 nm) single layer system and LSMO/γ-Fe2O3/LSMO (150 nm) trilayer heterostructures. In Insulating region, the deviations in the fitted curves from the experimental data is due to intrinsic disorder at the R/A site in case of LSMO single layer system while in case of trilayer system disorder exists at both R/A and B sites. The study is crucial to understand the microscopic picture of electrical transport behavior in both the systems near and above Metal-Insulator Transition.