Anisotropic hyperfine field fluctuation in Sr2FeMoO6

The double perovskite Sr2FeMoO6 has been studied by the Mossbauer technique, neutron, and x-ray diffraction. The structure is found to be tetragonal with lattice constants a(0) = 5.5729 Angstrom and c(0) = 7.9077 Angstrom. Mossbauer spectra and neutron diffraction measurements of Sr2FeMoO6 have been taken at various temperatures ranging from 10 to 473 K. The low-field magnetoresistance magnitude (Delta rho/rho (0)) at 500 Oe was 3.1% and 1.8% at 77 and 300 K, respectively. As the temperature increases toward to the Curie temperature, T-C = 425 K. Mossbauer spectra show the line broadening and 1, 6 and 3, 4 linewidth difference because of anisotropic hyperfine field fluctuation. The anisotropic field fluctuation of +H(P+ = 0.85) was great than -H(P- = 0.15). We also calculated frequency factor and anisotropy energy with values of 9.8 Gamma/(h) over bar and 149.6 erg/cm(3), respectively, using the relatively accurate data for T = 260 K which is associated with the large line broadening. (C) 2001 American Institute of Physics.