  We report the results from a 17O Nuclear Magnetic Resonance (NMR) study of
the high temperature superconducting cuprate (HTSC), RuSr2EuCu2O8. This
compound has recently been found to exhibit the coexistence of magnetic order
and superconductivity. At 9 T, the magnetic order in the RuO2 layers is
predominately ferromagnetic. We measured the 17O NMR spectra from 10 K to 330 K
and find the occurrence of an increasing 17O NMR shift with increasing
temperature for temperatures above ~200 K, providing direct evidence that
RuSr2RCu2O8 is similar to a very underdoped HTSC. The analysis of the NMR shift
and spectral width of the 17O NMR line gives a small but measurable hyperfine
field of ~9 mT from the Ru moment at the oxygen site in the copper oxygen
planes. We show that the 17O NMR linewidth is governed by dipolar contributions
from the Ru moment.
