STRUCTURAL, TRANSPORT AND MAGNETOTRANSPORT IN NONMAGNETIC <font>Al</font>³⁺ DOPED MIXED VALENT <font>La</font>_0.7<font>Ca</font>_0.3<font>Mn</font>_1-X<font>Al</font>_X<font>O</font>₃ MANGANITES

Abstract

We report the modifications in the transport and magnetotransport in La 0.7 Ca 0.3 Mn 1-x Al x O 3 (LCMAO); x = 0.0, 0.02, 0.04, 0.06, 0.08 and 0.1 polycrystalline manganites synthesized by conventional ceramic method. XRD studies reveal the single phasic orthorhombic structure for all the Al -doped LCMO samples without any detectable impurities and structural phase transition. SEM micrographs show island-like grain growth in all the samples studied. Transport measurements indicate an increase in resistivity and decrease in metal-insulator (M-I) transition temperature (T P ) with the increase in Al -concentration. Field and temperature dependent variation in MR for all the Al (x) doped LCMO samples has been discussed in detail in the light of substitution induced structural disorder.