In order to study the magnetoresistance effect of perovskitemanganite in low magnetic fields

manganite polycrystalline samples La0.7Ca0.3Mn1-xCrxO3(x=0

0.1) were prepared by solid-state reaction technique Resistance-temperature curves and magnetoresistance-temperaturecurves of the two samples were measured in zero magnetic field and 025 Tmagnetic field Influence of different substitution of Cr for Mn on low fieldmagnetoresistance effects of the samples was analyzed Experimental resultsshowed that the metal-insulatortransition temperature of the samples gradually moved to lower temperature andthe magnetoresistance peak temperature of the samples decreased from TP≈220K toTP≈190K withthe increase of Cr doping from x=0 to x=0.1. The samples showed largemagnetoresistance over liquid nitrogen temperature range in 0.25 T magneticfield.