Hur Su Gil, Park Dae Hoon, Hwang Seong-Ju, Kim Seung Joo, Lee J H, Lee Sang Young
Center for Intelligent Nano-Bio Materials (CINBM), Division of Nano Sciences and Department of Chemistry, Ewha Womans University, Seoul 120-750, Korea.
J Phys Chem B. 2005 Nov 24;109(46):21694-9. doi: 10.1021/jp054770e.
We have investigated the effect of alkaline earth metal substitution on the crystal structure and physical properties of magnetic superconductors RuSr(1.9)A(0.1)GdCu(2)O(8) (A = Ca, Sr, and Ba) in order to probe an interaction between the magnetic coupling of the RuO(2) layer and the superconductivity of the CuO(2) layer. X-ray diffraction and X-ray absorption spectroscopic analyses demonstrate that the isovalent substitution of Sr ions with Ca or Ba ions makes it possible to tune the interlayer distance between the CuO(2) and the RuO(2) layers. From the measurements of electrical resistance and magnetic susceptibility, it was found that, in contrast to negligible change of magnetization, both of the alkaline earth metal substitutions lead to a notable depression of zero-resistance temperature T(c) (DeltaT(c) approximately 17-19 K). On the basis of the absence of a systematic correlation between the T(c) and the interlayer distance/magnetization, we have concluded that the internal magnetic field of the RuO(2) layer has insignificant influence on the superconducting property of the CuO(2) layer in the ruthenocuprate.
我们研究了碱土金属替代对磁性超导体RuSr(1.9)A(0.1)GdCu(2)O(8)（A = Ca、Sr和Ba）晶体结构和物理性质的影响，以探究RuO(2)层的磁耦合与CuO(2)层的超导性之间的相互作用。X射线衍射和X射线吸收光谱分析表明，用Ca或Ba离子等价替代Sr离子能够调节CuO(2)层与RuO(2)层之间的层间距。通过电阻和磁化率测量发现，与磁化强度变化可忽略不计相反，两种碱土金属替代均导致零电阻温度T(c)显著降低（ΔT(c)约为17 - 19 K）。基于T(c)与层间距/磁化强度之间不存在系统相关性，我们得出结论：在钌铜酸盐中，RuO(2)层的内磁场对CuO(2)层的超导性能影响不大。
