The discovery of the coexistence of superconductivity and weak ferromagnetism in ruthenocuprates like (Ru, R-1222; R = Eu, Gd) and RuSr2GdCu2O8 (Ru-1212) has created a tremendous interest both experimentally as well as theoretically. Here, we have prepared polycrystalline samples of RuSr2R1.4Ce0.6Cu2O10 (R = Gd, Eu, and Sm) by the standard solid state reaction method. These samples were characterized by XRD, SEM, dc resistivity, and squid measurements. All the prepared samples were single phase without any trace of impurity. From the low-temperature resistivity measurement, the samples of (R = Eu and Gd) were found to be superconducting, while the samples of RuSr2Sm1.6Ce0.4Cu2O10 show semiconducting behavior. The magnetization (M) versus field (H) hysteresis at 5？K clearly shows the ferromagnetic behavior of the samples. The zero field cooled magnetization ( ) and field cooled magnetization ( ) diverge at 100？K. 1. Introduction The discovery of new superconducting and magnetic materials with anomalous properties has revived a significant activity in the field ranging from basic science to developments for technological applications. Usually, it was believed that for conventional superconductors described by the BCS theory [1] superconductivity (SC) and ferromagnetism (FM) are mutually antagonistic phenomena. However, the coexistence of SC and weak FM has been discovered in 1997 in (R = Eu, Gd, Ru-1222) [2] and subsequently in RuSr2GdCu2O8 (Ru-1212) [3, 4]. Ru-1222 is called superconducting weak ferromagnet because the SC arises in the FM ordered state [2]. Intensive research has been carried out to understand these magnetosuperconductors, particularly the Ru-1212 [3–7]. Ru-1212 displays a Curie transition at ？K and bulk superconductivity below 0–46？K depending on the sample preparations [3, 7]. Superconductivity appears to be associated with the CuO2 planes [6] with some types of long-range magnetic order that involves the RuO2 planes [4]. In comparison to Ru-1212, another magnetosuperconductor Ru-1222 was given less attention [8]. Ru-1222 has a complicated magnetic behavior. It is found to be paramagnetic at room temperature, but as it is cooled down, it undergoes antiferromagnetic transition [2, 8, 9] followed by spin glass behaviour [10] and ferromagnetic transition [2, 8, 9]. Below the ferromagnetic transition, the superconductivity sets in and coexists with the ferromagnetism. The tetragonal Ru-1222 structure evolves from the RBa2Cu3O7 (R-123) one by inserting a fluorite-type layer instead of single R layer in R-123. The Ru ions reside in the Cu(1)
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