Magnetic polaron mechanism of electron transport and magnetoresistance in spin systems: a Monte-Carlo simulation

A Monte-Carlo simulation of electron transport in a phase separated spin system in terms of itinerant electron tunneling between neighboring magnetic polarons is performed. The spin system is supposed to be a mixture of ferromagnetic metallic clusters embedded into the matrix of antiferromagnetic insulating phase. The simulation is based on a simple model on magnetic polarons in double exchange system. The co-occurrence of insulating-metallic transition and ferromagnetic transition with decreasing temperature is observed and a giant magnetoresistance around the transition is demonstrated. The present model presents a simple approach to the electron transport in phase-separated spin systems with itinerant electron conduction, such as manganites.