ACTA

Local Magnetic and Electronic Properties of the A2FeM'O6 (A = Ba, Sr, Ca, M' = Mo, Re) Double Perovskites

D. Zając^a, M. Sikora^a, V. Prochazka^a, M. Borowiec^a, J. Stpie^a, Cz. Kapusta^a, P.C. Riedi^b, C. Marquina^c, J.M. De Teresa^{c, d} and M.R. Ibarra^{c, d}
^aAGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. Mickiewicza 30, 30-059 Kraków, Poland
^bDepartment of Physics & Astronomy, University of St. Andrews, St. Andrews, Fife, KY16 9SS, Scotland, UK
^cUniversidad de Zaragoza-CSIC, Facultad de Ciencias, Pedro Cerbuna 12, Zaragoza 50009, Spain,
^dInstituto de Nanociencia de Aragon, Universidad de Zaragoza (INA), Pedro Cerbuna 12, Zaragoza 50009, Spain

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Received: 14 09 2006;

The results of a combined NMR, X-ray absorption spectroscopy and X-ray magnetic cirrcular dichroism study of the AA'FeMoO₆ and AA'FeReO₆ double perovskites are presented. They revealed a dependence of electronic and magnetic properties, including a d-electron transfer between Fe and Mo sites, on the structural tolerance factor. The maximum value of the 4d Mo electron occupation and the corresponding Mo moment is obtained for the tolerance factor of unity. This corresponds to the maximum strength of the magnetic interaction and, respectively, to the Curie temperature. The dominant T^5/2 type temperature dependence of the Mo hyperfine field reveals the half-metallicity of the AA'FeMoO₆ compounds. Antisite defects and antiphase boundaries have been identified in NMR measurements and the strength of their magnetic coupling have been determined. A considerable orbital contribution to the Re and Fe magnetic moments were found in the NMR and X-MCD measurements on the AA'FeReO₆ compounds. Its magnitude decreases with increasing structural tolerance factor and is correlated with their magnetic anisotropy.

DOI: 10.12693/APhysPolA.111.797
PACS numbers: 75.30.-m, 76.60.-k, 76.60.Jx, 78.80.En