高温超导体中磁通涡旋薄饼运动的实验证明

为了验证高温超导体中涡旋薄饼运动的存在,我们设计了电流和电位引线分处样品不同表面的实验。实验结果表明,在这种电流电位引线配置下的E～j关系不同于刚性涡旋线运动所预期的E～j关系,由此支持了涡旋薄饼运动的存在。     

高温超导体磁通跳跃数值模拟

文中基于超导磁通动力学理论,考虑电磁力与热激活对磁通运动的影响,基本物理模型由等效电阻率随超导体温度和磁场变化的磁通扩散方程,以及比热随超导体温度变化的热传导方程组成。在此基础上,用差分法数值求解了这一复杂非线性系统的磁热耦合控制方程,得到了与实验观测结果基本一致的数值模拟结果。结果还表明：外加磁场变化速度、超导体初始温度以及超导尺寸对于磁通跳跃均产生明显的影响。     

稀土在中国高新材料研制开发中的应用

我国在稀土资源和稀土原料的生产方面都居世界领先地位，近年来稀土高新材料的研制与开发也取得重大进展。本文概述了我国在稀土高新材料开发与研究方面的成果，指出今后应把稀土应用基础研究、中重稀土的应用研究和稀土在能源领域的应用研究作为重点进一步开展工作。     

The decomposition of the oxalate precursor and the stability and reduction of the YBa2Cu4O8 superconductor studied by TG coupled with FTIR and by XRD

The 124 superconductor YBa₂Cu₄O₈ was prepared from the oxalate precursor Y₂(C₂O₄)₃. ·4BaC₂O₄·8CuC₂O₄·xH₂O at one atmosphere oxygen pressure. In O₂ the precursor decomposes in one step at 300°C and more gradually (300°–600°C) in Ar. The stability of the superconductor is strongly dependent on the gas atmosphere: in O₂ and in air there is no significant weight change as long as the temperature does not exceed 800°C, whereas in a 1% O₂-99%N₂ mixture decomposition starts at about 670°C with the formation of CuO and YBa₂Cu₃O_x withx<7. The reduction of YBa₂Cu₄O₈ in a 5% H₂-95% Ar mixture takes place in at least four major steps with formation of products such as Y₂O₃, BaO, Cu₂O, Cu, BaY₂O₄ and Ba₄Y₂O₇.     

Studies of heterogeneity properties of selected high-temperature superconductor surfaces

Nitrogen adsorption measured at 77 K was used to characterize the surface heterogeneity of high-temperature superconductor surfaces. Properties relating to adsorption and porosity of the solids (adsorption capacity, specific surface area, radii and volume of the pores, pore-size distribution function) were determined from nitrogen adsorption–desorption isotherms and atomic force microscopy (AFM) for a series of oxide superconductors. It is shown that the adsorption isotherms of all samples are S-shaped and belong to type II according to the IUPAC classification. On the basis of the nitrogen adsorption isotherms and AFM data, fractal dimensions were determined and correlations found with adsorption and porosity parameters.     

名义组分为Y_6Ba_(11)Cu_(16)O_x的纳米超导材料

采用柠檬酸盐热分解法制备了名义组分为Y6Ba11Cu16Ox的纳米超导材料。利用XRD对其粉体进行物相表征,发现其相是Y123和Y211的混合相,并测得两者之间的摩尔比为1∶0.14,同时把其XRD图谱与Y1Ba2Cu3O7-x的XRD图谱进行了对照分析。利用标准的四端引线法对其块体进行R-T分析,测出其起始转变温度Tonset=86.0K,转变宽度△Tc=6.7K,并表现出良好的超导电性,也相应地把其与Y1Ba2Cu3O7-x进行了对比。根据Scherrer公式计算得到样品的平均晶粒尺寸约为67.1nm。文中也分析了所制材料为混合物的原因。     

超导电力技术新进展及其未来发展的思考

近年来高温超导材料研究取得很大进展,它在电力领域的应用研究已受到广泛关注,一些示范样机,诸如高温超导输电电缆、变压器、故障电流限制器、电机和储能装置已经研制成功并投入示范性试验.超导技术是21世纪具有战略经济意义的高新技术,文章将介绍高温超导电力应用研究的新进展及其未来发展的思考。     

Majorana fermions induced fast- and slow-light in a hybrid semiconducting nanowire/superconductor device

We investigate theoretically Rabi-like splitting and Fano resonance in absorption spectra of quantum dots(QDs)based on a hybrid QD-semiconducting nanowire/superconductor(SNW/SC)device mediated by Majorana fermions(MFs).Under the condition of pump on-resonance and off-resonance,the absorption spectrum experiences the conversion from Fano resonance to Rabi-like splitting in different parametric regimes.In addition,the Fano resonances are accompanied by the rapid normal phase dispersion,which will indicate the coherent optical propagation.The results indicate that the group velocity index is tunable with controlling the interaction between the QD and MFs,which can reach the conversion between the fast-and slow-light.Fano resonance will be another method to detect MFs and our research may indicate prospective applications in quantum information processing based on the hybrid QD-SNW/SC devices.     

Mean-field calculations on the magnetic properties of the two-gap superconductor Lu2Fe3Si5

Based on Ginzburg-Landau theory, we study the temperature dependence of upper critical field and London penetration depth for the superconducting crystal Lu₂Fe₃Si₅. All the results fit the experimental data well. We also indicate that the larger gap opens in the quasi-one-dimensional part of Fermi surfaces.