Suppression of Charge and Antiferromagnetic Ordering in La0.5Ca0.5MnO3 Nanoparticles
The intermediate band-width manganite La0.5Ca0.5MnO3 has a CE type charge, orbital and antiferromagnetic order below 195 K owing to strong electronic correlation and commensurability effect. We have critically investigated in details all the possible
mechanisms behind the destabilization of charge/orbital ordering in La0.5Ca0.5MnO3 with the reduction of grain size in the nanometric regime as evidenced from our various experimental results. We have tried to found out a universal scenario to explain such
behavior in nanometric manganites in general. This study shows that the room temperature Pnma perovskite structure, correlated with the lattice distortion, Mn–O distances and octahedral tilts, is practically unaffected with the reduction of particle size. However, in these nanocrystalline
La0.5Ca0.5MnO3, the stable charge ordered state with antiferromagnetic ordering becomes significantly suppressed and FM ordering spontaneously appears below T
C = 260 K as compared to its bulk counterpart. From strong experimental evidences
on nano and bulk manganites, we revisit this issue and also discuss the absence of correlation between size reduction and pressure effects on manganites. We argue from a phenomenological analysis that the above observations could be best attributed to enhanced surface disorder in the nanosized
half-doped manganite grains which is likely to be general in all nano size charge ordered manganites.
Keywords: CE-TYPE ANTIFERROMAGNETISM; CORE–SHELL STRUCTURE; NANOSTRUCTURED MANGANITES; SUPPRESSION OF CHARGE ORDERING; SURFACE DISORDER
Document Type: Research Article
Publication date: 01 June 2011
- Journal for Nanoscience and Nanotechnology (JNN) is an international and multidisciplinary peer-reviewed journal with a wide-ranging coverage, consolidating research activities in all areas of nanoscience and nanotechnology into a single and unique reference source. JNN is the first cross-disciplinary journal to publish original full research articles, rapid communications of important new scientific and technological findings, timely state-of-the-art reviews with author's photo and short biography, and current research news encompassing the fundamental and applied research in all disciplines of science, engineering and medicine.
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