NMR Study of (Sr,Ba,La)2Fe1+yMo1-yO6 Double Perovskites

D. Zająca, Cz. Kapustaa, P.C. Riedib, M. Sikoraa, C.J. Oatesa, D. Rybickia, J.M. De Teresac, D. Serratec, C. Marquinac and M.R. Ibarrac aDepartment of Solid State Physics, Faculty of Physics and Nuclear Techniques, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Cracow, Poland bDepartment of Physics and Astronomy, University of St. Andrews, St. Andrews, KY16 9SS Scotland, UK cInstituto de Ciencia de Materiales de Aragóon, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain

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The 95Mo and 97Mo NMR spin-echo study of (Sr,Ba,La)2Fe1+yMo1-yO6 double perovskites is reported. Powder samples of Ba1.44Sr0.36La0.2FeMoO6 and (Ba0.8Sr0.2)2-2xLax#x Fe1+yMo1-yO6, where# denotes vacancies, for: x=0, y=0; x=0.1, x=0.2 and x=0.3, y=0 and y=0.2 were measured at 4.2 K and no applied magnetic field. NMR signals are observed at 55-100 MHz for the main line and 30-55 MHz for low-frequency satellite. The main line and the satellite are attributed to the ideal and defect positions of Mo atoms. La and vacancy doping introduce more defects, however, increasing the Fe/Mo ratio decreases the amount of defect Mo sites. La doping causes a satellite pattern at the high frequency side of the spectrum, which is related to different numbers of the La next neighbours. The effect is attributed to an increase in the electron density and the corresponding magnetic moment at the adjacent Mo sites and reveals a local character of the electron doping.

DOI: 10.12693/APhysPolA.106.759 PACS numbers: 75.25.+z, 76.60.-k, 78.70.Gq, 75.47.Gk