  95, 97Mo NMR experiments have been performed on a series of Sr2FeMoO6 and
electron-doped Sr2-xLaxFeMoO6 ceramics. Detailed analysis of the NMR spectra
from pristine Sr2FeMoO6 conclusively shows that the Mo hyperfine field is
mainly due to atomic Mo magnetic moments. No contribution of transferred
hyperfine field has been observed, confirming the absence of s-electrons in the
conduction band. Upon La doping, the NMR frequency (hyperfine field) gradually
increases proving that the concentration of spin polarized electrons at Mo ion
is enhanced by the La substitution. A simple linear correlation between
magnetic moment at Mo sites and the Curie temperature of the system has been
found. Implications for understanding the electronic structure and the
ferromagnetic coupling in these systems are underlined.
