We report resistivity data on ceramic RuSr2Gd2-xCex Cu2O10-δ which is the first Cu-O based system in which superconductivity (SC) in the CuO2 planes and weak-ferromagnetism (W-FM) in the Ru sublattice are considered to coexist. Due to the granular nature of the materials the critical current density at 5 K is extremely small as compared to other high-TC superconducting materials. Below the superconducting transition (TC), the magnetoresistance ΔR(H) = R(H)-R(0) is positive and unexpected hysteresis loops are observed. The hysteresis loop is completely different than that observed in conventional homogeneous superconductors. ΔR(H) on decreasing the applied field (Hext) is much smaller than the ΔR(H) for increasing (Hext). The width of the loops depends strongly on the weak-link properties. Similar hysteresis loops are observed in the reference nonmagnetic NbSr2Gd1.5Ce0.5Cu2O10 which is SC at TC=28 K, thus the possibility that the hysteresis phenomenom is caused by the coexistence of both SC and magnetic states is excluded.
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|Physical Review B - Condensed Matter and Materials Physics
|Published - 2003 4月
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