Effect of Nb doping on superconducting and magnetic properties of RuSr2(Gd1.5-yEuyCe0. 5)Cu2Oz

초록

We performed resistivity and magnetization measurements on the ruthenocuprates (Ru1-xNbx)Sr-2(Gd1.4Ce0.6)-Cu2Oz (x = 0-0.5) and (Ru0.5Nb0.5)Sr-2(Gd1.5-yEuyCe0.5)Cu2Oz (y = 0-1.5). It is found that the Nb substitution for Ru depresses superconductivity only slightly from T-c=27K for x=0 to T-c = 24K for x = 0.5, but significantly reduces the ferromagnetic component. In contrast to the Nb-free sample, a partial evolution of the Meissner state followed by a reentrance of the magnetization is observed in the field-cooled magnetization measurements of the Nb-doped samples. The magnetization measurements on the (Ru0.5Nb0.5)Sr-2(Gd1.5-yEuyCe0.5)Cu2O, system indicate that the reentrant behavior of the magnetization below T. is caused by the paramagnetic contribution of the Gd3+ ions and the Meissner effect can be seen more clearly after suppressing the paramagnetic response of the sublattice of Gd3+ ions. (C) 2004 Elsevier B.V. All rights reserved.

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