  The macroscopic magnetizations of Ru_1-xCu_xSr_2EuCu_2O_8+d with x between 0
and 0.15 were investigated. A ferromagnet-like transition as well as an
antiferromagnet-like transition appear around T_M in the low-field
magnetization and around T_AM in the high-field differential susceptibility,
respectively. The separation between them, which is accompanied by a flat
plateau in the magnetic C_p, increases with x. Superparamagnetic M(H) and slow
spin dynamics, i.e. characteristics of nanomagnetic clusters, were observed far
above T_M. A comparison with RuSr_2(Eu_1-yCe_y)Cu_2O_10+d and some manganites
further suggests that a phase separation occurs, which can describe well the
conflicting magnetic-superconductivity data previously reported.
