Spin fluctuation and small polaron conduction dominated electrical resistivity in La0.875Sr0.125MnO3 manganite nanostructures

Abstract

The anomalous temperature-dependent electrical resistivity ρ(T) of La0.875Sr0.125MnO3 manganite nanoparticles (particle size 18 nm) is theoretically analysed. ρ(T) exhibits semiconducting phase in low-temperature regime (20 K < T < 53 K), shows a minima near 53 K and increases with T at high temperatures (53 K < T < 170 K). The resistivity in metallic phase (T > 53 K) is theoretically analysed by considering the strong spin-fluctuation effect, which is modelled using Drude-Lorentz type function. In addition to the spin fluctuation-induced contribution, the electron-phonon and electron-electron ρ e−e(T) = BT 2 contributions are also incorporated for complete understanding of experimental data. The contributions to the resistivity by inherent acoustic phonons (ρ ac) as well as high-frequency optical phonons (ρ op) were estimated using Bloch-Gruneisen (BG) model of resistivity. It is observed that the resistivity contribution due to electron-electron interaction shows typical quadratic temperature dependence. Spin fluctuation-induced resistivity is dominant over electron-electron and electron-phonon contributions in overall temperature range in the manganite nanoparticles. Resistivity in the semiconducting phase is discussed with small polaron conduction (SPC) model. SPC model consistently retraces the low-temperature resistivity behaviour (T < 53 K). Finally, the theoretically calculated resistivity compared with experimental data is found to be consistent in wide range of temperature.