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Title: Effect of bandwidth and size disorder on the electrical and magnetotransport properties of doped LaMnO3 perovskite
Authors: Thaker, C M
Rana, D S
Mavani, Krushna
Patil, S I
Sahasrabudhe, M
Kuberkar, D G
Issue Date: Aug-2003
Publisher: NISCAIR-CSIR, India
Abstract: Structural, electrical, magnetic and magnetotransport measurements have been carried out on La1-2x PrxCaxMnO3: x =0.20 and 0.30 manganite compounds. These samples form in a distorted orthorhombic structure and behave as nearly low bandwidth systems. Both these samples exhibit insulator-metal transition below 120 K with a large colossal magnetoresistance (CMR) effect at relatively weaker fields (MR=75% at 1 Tesla for x = 0.30 sample).We have also studied the structural, transport and magnetotransport properties of a larger size cation, Sr2+, substituted La0.5Pr0.2Ca0.3-xSrxMnO3(0.0≤x≤0.20) compounds. It is observed that increasing Sr2+ substitution results in an enhancement in transition temperature with a subsequent fall in MR%. The insulator-metal transition temperature for these samples increases from 138 K for x=0.0 to 252 K for x=0.20. The CMR effect fall from 46% for x=0.0 to less than 10% for x=0.20 at a field of 1 Tesla. Also, for samples with higher Sr content the MR% at low temperature is comparable to the MR% in the vicinity of peak resistance. The resistance data in the semiconducting region of all the samples obeys the Mott’s Variable Range Hopping type(lnR  T0.25) of conduction mechanism.
Page(s): 324-328
ISSN: 0975-1017 (Online); 0971-4588 (Print)
Appears in Collections:IJEMS Vol.10(4) [August 2003]

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