Superconductivty and magnetic properties of (Ru1-xNbx)Sr2(Sm1.4Ce0.6)Cu2Oz

초록

We investigated the effect of Nb substitution for Ru on the structural and magnetic properties of (Ru<inf>1-x</inf>Nb<inf>x</inf>) Sr2(Sm<inf>1.4</inf>Ce<inf>0.6</inf>)Cu<inf>2</inf>O<inf>z</inf> Samples. X-ray diffraction measurements indicated that nearly single-phase samples are formed in the range from x = 0 to 1.0. The superconducting transition temperature determined from the inflection in the field-cooled magnetic susceptibility decreased only slightly from T<inf>c</inf> = 25 K for x = 0 to T<inf>c</inf> = 22 K for x = 1.0, in consistent with the change in room temperature thermopower of the samples. However, the Nb substitution for Ru above x = 0.25 significantly suppressed the weak ferromagnetic component of the field-cooled magnetic susceptibility. It was also found that the Nb substitution for Ru results in an enhanced diamagnetic susceptibility with Nb content above x = 0.5 in both zero field-cooled and field-cooled magnetization measurements, in contrast to the behavior of the samples with x ≤ 0.5 in which the diamagnetic susceptibility decreases as the Nb content increases.

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