Origins of both insulator–metal transition and colossal magnetoresistance in doped manganese perovskites

Abstract

Based on experiments of both transport and paramagnetic resonance for (La1−xYx)2/3Ca1/3MnO3, the ground state above Tc and possible origins of both insulator–metal transition and colossal magnetoresistance near Tc are discussed. Modeling the system as a network of junctions, each consisting of a paramagnetic region sandwiched between two ferromagnetic domains, a phenomenological expression is proposed for resistance as a function of temperature and magnetic field. We show that the observed transport and magnetotransport phenomena can be quantitatively explained by the present model for the whole temperature range studied.