Investigation of Proximity Effects between Normal Metal and Superconductor through Transmission Electron Spin Resonance and Microwave Magnetoabsorption

这个项目的结果，把超导体和共振/非共振微波之间的相互作用作为一个主线，总结如下。(1)制作简单的电阻率低温恒温器和Y基和Bi基高t_c超导体，为YBCO情况下的电子束蒸发提供了相当满意的源材料。然而，在BSCCO的情况下，改善样品内氧浓度的均匀性还存在一些问题。(2)通过x射线衍射和Rietveld分析，主要证实了YBCO中烧结条件、氧含量和超导性质之间的密切关系。这是研究钉钉缺陷与缺氧之间关系的重要一步。(3)指出了超导性的急剧转变和正常金属与超导体之间的适度耦合的必要性，以便通过透射率的测量清楚地观察到明显的接近效应。(4)详细的微波磁吸收观测表明，l基铜酸盐的超导性与bi基铜酸盐相似，具有准二维超导性。观测到H_<FC>场冷却后的残余吸收和现有场H_a下的磁吸收的对数弛豫，分别为U_O α H^<-1/4>_和U_O α H^<-1/2>_提供了磁钉钉势U_O的估计。这些观测结果与微波不可逆性测量结果一致，U_O α B^<-1/2>依赖于二维通量晶格模型。场内微波吸收的衰减过程进一步表明，更大场内的吸收与磁化强度|M|密切相关，而不是与磁通密度b密切相关。在未来的项目中，微波与超导体之间的相互作用将在相同样品的磁化强度测量中继续进行进一步的研究。少

The results of this project, regarding the interaction between superconductors and resonant / non-resonant microwaves as an woof, is summarized below.(1) Fabrication of a simple resistivity cryostat and Y- and Bi- based high-T_c superconductors resulted in a fairly satisfying source material for electron-beam evaporation in YBCO case. In BSCCO case, however, there remained some problems for improving homogeneity of oxygen concentration within the sample.(2) Close correlations among sintering conditions, oxygen contents and superconducting qualities have been confirmed mainly in YBCO through X-ray diffraction and Rietveld analyses. This has been one step towards studies of correlation between flux-pinning defects and oxygen deficiency.(3) The necessity of rather sharp transition of superconductivity as well as moderate coupling between normal metal and superconductor has been pointed out for the distinct proximity effect to be clearly observed through measurements of the transmission el … More ectron spin resonance.(4) The detailed observations of the microwave magnetoabsorption have shown that superconductivity in the Tl-based cuprate is quasi-two dimensional similar to the Bi-based cuprate. The observed logarithmic relaxations in the remanent absorption after H_<FC> field cooling and in the magnetoabsorption under existing field H_a provided estimations of the flux pinning potential U_O which scaled as U_O alpha H^<-1/4>_ and as U_O alpha H^<-1/2>_, respectively. These observations are consistent with the microwave irreversibility measurements with U_O alpha B^<-1/2> dependence which originates in the two-dimensional flux lattice model. Decaying process of the in-field microwave absorption further suggested that the absorption in larger applied field is closely correlated with magnetization |M| rather than flux density B. Further investigations on the interactions between microwaves and superconductors will be continued in the future project accompanied by magnetization measurements in the same samples. Less