Effect Of Cr Substitution On The Magnetotransport Properties Of La0.7Ca0.3MnO3.

The structure and phase purity of powder La_0.7Ca_0.3Mn_1-xCr_xO₃ (x = 0.075, 0.15, 0.3), has been by checked by X-ray diffraction. Effects of Cr doping on the magnetic and transport properties are studied in the range 300—4 K in the absence and presence of 0.7 T magnetic field. All the samples show metral-insulator transition behaviour with a peak in the electrical resistivity as the temperature is decreased. For increasing doping concentration an increase in resistivity, a decrease the resistivity peak temperature to the metal-insulator transition and an increase in low temperature intrinsic magnetoresistance is observed. The activation energy which explains the insulating like behaviour of resistivity above transition temperature is calculated and compared with the Cr concentration. [ABSTRACT FROM AUTHOR]