Electrical transport in the ferromagnetic and paramagnetic state of potassium-substituted manganites La1−x K x MnO3 (x = 0.05, 0.1 and 0.15)

Abstract

We report the analysis of resistivity in the ferromagnetic and paramagnetic state of La1−x K x MnO3 (x = 0.05, 0.10 and 0.15). The phonon frequencies are estimated from the ab initio theory with calibrated Hamiltonian for the atomic interaction between a pair such as Mn–O and La/K–O including van der Walls interaction. The modified electron–phonon (acoustic and optic) scattering incorporating the statistical factor and electron–electron and electron–magnon interactions is effective to describe the resistivity behaviour for a temperatures less than the metal–insulator transition (T P) in the ferromagnetic state of La1−x K x MnO3 (x = 0.05, 0.10 and 0.15). The Mott–Ioffe–Regel criterion for metallic conductivity is valid, and k F l ~ 1, e F τ ~ 1. Paramagnetic semiconducting resistivity is consistent with small polaron conduction model, and variable-range hopping is inappropriate for the description of resistivity behaviour in a high-temperature region, T > T P. The results suggest that disorder-induced localisation of charge carriers dominates electrical transport.