CUED Publications database

La 0.7Ca 0.3MnO 3 / Mn 3O 4 composites: Does an insulating secondary phase always enhance the low field magnetoresistance of manganites

Bhame, SD and Fagnard, J-F and Pekala, M and Vanderbemden, P and Vertruyen, B (2012) La 0.7Ca 0.3MnO 3 / Mn 3O 4 composites: Does an insulating secondary phase always enhance the low field magnetoresistance of manganites. Journal of Applied Physics, 111. ISSN 0021-8979

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Abstract

Composites of magnetoresistive La 0.7Ca 0.3MnO 3 (LCMO) with insulating Mn 3O 4 are useful as a model system because no foreign cation is introduced in the LCMO phase by interdiffusion during the heat treatment. Here we report the magnetotransport properties as a function of sintering temperature T sinter for a fixed LCMO/Mn 3O 4 ratio. Decreasing T sinter from 1250 °C to 800 °C causes an increase in low field magnetoresistance (LFMR) that correlates with the decrease in crystallite size (CS) of the LCMO phase. When plotting LFMR at (77 K, 0.5 T) versus 1/CS, we find that the data for the LCMO/Mn 3O 4 composites sintered between 800 °C and 1250 °C follow the same trend line as data from the literature for pure LCMO samples with crystallite size >∼25 nm. This differs from the LFMR enhancement observed by many authors in the usual manganite composites, i.e., composites where the insulating phase contains cations other than La, Ca or Mn. This difference suggests that diffusion of foreign cations into the grain boundary region is a necessary ingredient for the enhanced LFMR. © 2012 American Institute of Physics.

Item Type: Article
Subjects: UNSPECIFIED
Divisions: Div B > Electronics, Power & Energy Conversion
Depositing User: Cron Job
Date Deposited: 07 Mar 2014 12:00
Last Modified: 08 Dec 2014 02:22
DOI: 10.1063/1.3694664