Spin gap characteristic of Y(Ba1-xGdx)(2)Cu3O7-delta

Y(Ba1-xGdx)(2)Cu3O7-delta compounds With x = 0 similar to 0.15 are prepared using the solid reaction technique. With structure analysis by Rietveld re finement of x-ray diffraction, we find that Gd3+ ions prefer to occupy Y si tes within lighter doping x less than or equal to 0.08 due to ion size effe cts, then begin partially to occupy Ba sites with doping content increasing , which gives vital influence on superconductivity and spin-gap properties. The magnetic doping effects of Gd3+ ions on spin-gap properties are invest igated in detail by contrast of the distinguished behaviors between T* and T-c, indicating that spin-gap temperature is not completely determined by t he carrier density, but strongly dependent on the strength of interplane an tiferromagnetic coupling. Finally, we propose an expression of in-plane res istivity dependent on the maximal width of spin-gap Delta(0) to derive thei r values for different samples, which almost keep constant with the increas e of Gd doping contents.