A 55 Mn NMR Study of La 0.33 Nd 0.33 Ca 0.34 MnO 3 with 16 O and 18 O

D. Rybicki a , Cz. Kapusta a , P.C. Riedi b , C.J. Oates a , M. Sikora a , D. Zając a , J.M. De Teresa c , C. Marquina c and M.R. Ibarra c a Department of Solid State Physics, Faculty of Physics and Nuclear Techniques, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Cracow, Poland b Department of Physics and Astronomy, University of St. Andrews, St. Andrews, KY16 9SS, Scotland, United Kingdom c Instituto de Ciencias de Materiales de Aragon, Universidad de Zaragoza CSIC, 50009 Zaragoza, Spain

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A 55 Mn NMR study of 16 O and 18 O containing La 0.33 Nd 0.33 Ca 0.34 MnO 3 is reported. The spin-echo spectra measured at 4.2K and zero field consist of a double exchange line corresponding to the ferromagnetic metallic regions. The line intensity is more than an order of magnitude lower for the 18 O compound, which indicates an order of magnitude lower content of the ferromagnetic metallic phase in this compound. The frequency dependence of the spin--spin relaxation time T 2 shows a pronounced minimum at the center of the double exchange line of both compounds due to the Suhl--Nakamura interaction, which indicates that the ferromagnetic metallic regions are at least 10nm in size. The results are discussed in terms of the influence of oxygen isotopic substitution on phase segregation.

DOI: 10.12693/APhysPolA.105.183 PACS numbers: 76.60.--k, 75.47.Gk