  The macroscopic magnetizations of a RuSr2(Eu0.7Ce0.3)2Cu2O10+d sample were
investigated. A ferromagnet-like transition occurs around T_M in the low-field
magnetization. Highly nonlinear M(H), non-Curie-Weiss susceptibility, and slow
spin-dynamics, however, were observed up to T_1 approx 2-3 T_M. In addition, an
antiferromagnet-like differential-susceptibility maximum of Ru appears around a
separate temperature T_AM between T_1 and T_M. The data are therefore
consistent with a phase-separation model: superparamagnetic clusters (or
short-range spin-orders) are first precipitated from the paramagnetic matrix
below T_1, followed by an antiferromagnetic transition of the matrix at T_AM
and an apparent ferromagnetic (FM) transition around T_M, where the long-range
spin-order is established in the FM species imbedded in the matrix.
