The La1-xBaxMnO3 for 0.5 less than or equal to x was found to be an intrinsic magnetic granular system composed of ferromagnetic/metallic phase and insulating phase. Owing to the magnetic granularity, the La1-xBaxMnO3 system for 0.5 less than or equal to x shows a three-dimensional percolation-type conduction behavior with a percolation threshold of x(p) = similar to0.85 (i.e. ferromagnetic volume fraction, theta (p)(), of similar to 17) and a large low field magnetoresistance (MR). The MR of 12-16 at 500 Oe and 77 K was found in the granular ferromagnetic region over a wide range of doping 0.5 less than or equal to x less than or equal to 0.75, and the MR was found to become small for x 0.75. (C) 2001 Elsevier Science Ltd. All rights reserved. References: 15
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