Effect of La substitution on the superconducting and magnetic properties of RuSr2(Eu1.5Ce0.5)Cu2Oz

초록

Polycrystalline samples Of Ru(Sr2-xLax)(Eu1.5Ce0.5)Cu2Oz and (Ru0.5Nb0.5)(Sr2-xLax)(Eu-1.5 Ce-0.5)Cu2Ox (0 less than or equal to x less than or equal to 0.2) are synthesized to study the effects of La doping on the superconducting and magnetic properties of the Ru-1222-type compound which is a ferromagnetic superconductor. We find that, in contrast to the studies on Ru(Sr2-xLax)RCu2Ox (R. = Gd, Eu), there is no indication of an increase in the magnetic ordering temperature when La is substituted for Sr in the Ru(Sr2-xLax)(Eu1.5Ce0.5)Cu2Ox system. However, increasing the La content has the effects of increasing the normal state resistivity and slightly decreasing the T,. These features are also observed for the (Ru0.5Nb0.5)(Sr2-xLax)(Eu1.5Ce0.5)Cu2Oz system, in which the Nb substitution for Ru significantly reduces the ferromagnetic component of the magnetization, suggesting that the La-doping effects on superconductivity are insensitive to the magnetic ordering of Ru ions.

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