Field-induced crossover and colossal magnetoresistance in La{sub}0.7Pb{sub}0.3MnO{sub}3

摘要

A field-induced crossover is observed in the resistivity (ρ) and magnetization (M) of a La{sub}0.7Pb{sub}0.3MnO{sub}3 single crystal. The field-dependence of ρ and M suggests that a small spin-canted species with mean-field-like interactions dominates at low fields (H), whereas individual spins and 3D Ising/Heisenberg models describe the high-H behavior rather well. Around the ferromagnetic transition, an H-induced destruction of the small spin-canted magnetic polarons is accompanied by large magnetoresistance.