Influence of the Grain Size on Polaron Transport in Nanostructured La2/3Ca1/3MnO3 Evidenced by EPR

O. Raitaa, M.N. Grecub, X. Filip, D. Tolomana, M. Giurgiua, Idziakc and Hoffmannc aNational Institute for Research and Development of Isotopic and Molecular, Technologies, P.O. Box 700, 400293, Cluj-Napoca, Romania bNational Institute for Material Physics, 76900 Bucharest-Magurele, Romania cInstitute of Molecular Physics, Polish Academy of Sciences, 60-179 Poznań, Poland

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Received: 24 04 2005;

We report an electron paramagnetic resonance investigation of the grain size effects on the polaron transport in the paramagnetic regime of nanosized La2/3 Ca1/3MnO3 manganites. The temperature dependences of the EPR integral intensity were analyzed in terms of spin-spin exchange interaction and small polaron hopping scenarios. The polaron activation energy decreases with the reduction of the grain size. A discussion is given concerning the factors which could explain the observed change.

DOI: 10.12693/APhysPolA.108.113 PACS numbers:75.50.Tt, 73.63.Bd, 76.50.+g