Magnetic Transitions and Ferromagnetic Clusters in RuSr2(Eu,Ce)2Cu2O10+d

الأصل · EN

The macroscopic magnetizations of a RuSr2(Eu0.7Ce0.3)2Cu2O10+d sample were investigated. A ferromagnet-like transition occurs around Tₘ in the low-field magnetization. Highly nonlinear M(H), non-Curie-Weiss susceptibility, and slow spin-dynamics, however, were observed up to T₁ approx 2-3 Tₘ. In addition, an antiferromagnet-like differential-susceptibility maximum of Ru appears around a separate temperature TₐM between T₁ and Tₘ. 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 T₁, followed by an antiferromagnetic transition of the matrix at TₐM and an apparent ferromagnetic (FM) transition around Tₘ, where the long-range spin-order is established in the FM species imbedded in the matrix.