  In order to investigate the coexistence of magnetism and superconductivity on
a microscopic scale, local studies using zero-field spin-echo ^{99,101}Ru NMR
and ^{63,65}Cu NQR have been carried out on both superconducting and
non-superconducting samples of magnetically ordered RuSr_{2}EuCu_{2}O_{8} and
RuSr_{2}GdCu_{2}O_{8}. ^{99,101}Ru NMR signals were observed at 1.3 K over two
distinct frequency ranges. The high frequency spectra (110 to 150 MHz), which
are essentially the same for all samples, are characterized by five sharp peaks
for each isotope corresponding to a hyperfine field of approximately 590 kOe
with the appropriate quadrupole splitting. The low frequency spectra (40 to 90
MHz), which show significant variation from sample to sample, correspond to a
much lower hyperfine field with considerable broadening and quadrupole features
that are barely resolvable. As reported previously, the low frequency spectra
are attributed to the Ru^{4+} valence state while the high frequency spectra
are attributed to the Ru^{5+} valence state. ^{63,65}Cu NQR features were
observed (26 to 34 MHz), although with considerable broadening. The results are
discussed in terms of the microscopic magnetic structure, mixed valence state
for Ru, occupancy of the Ru sites, and the existence and role of impurity
phases.
