Percolative magnetotransport and enhanced intergranular magnetoresistance in a correlated resistor network

Based on phase separation and intergranular tunneling, a correlated resistor network model is proposed to simulate the percolative magnetotransport in some spontaneously phase-separated perovskite oxides and their artificial granular composites. For the inclusion of spin-dependent transport mechanism in a network with correlated structure, a directed tunneling percolation scenario is established for the magnetotransport in these oxides, instead of the previous two-component metal-to-insulator percolative description in a random resistor network. Within this framework, the concentration dependence of intergranular magnetoresistance in these mixed-phase materials is well explained and the mechanism to the largest magnetoresistive effects is revealed.