High-temperature superconductivity

About: High-temperature superconductivity is a research topic. Over the lifetime, 7263 publications have been published within this topic receiving 175377 citations. The topic is also known as: high-temperature superconductivity.

Monotonic d -wave superconducting gap of the optimally doped Bi 2 Sr 1.6 La 0.4 CuO 6 superconductor by laser-based angle-resolved photoemission spectroscopy

Abstract: We propose that the upper Hubbard band (electronlike) and the Zhang-Rice singlet band (holelike) are two essential components in describing low-energy excitations of electron-doped cuprate superconductors. We find that the gap between these two bands is significantly smaller than the charge-transfer gap measured by optics and is further reduced upon doping. This indicates that the charge fluctuation is strong and the system is in the intermediate correlation regime. A two-band model is derived. In the limit that the intraband and interband hopping integrals are equal to each other, this model is equivalent to the unconstrained t-J model with on-site Coulomb repulsions.

The problem of high-temperature superconductivity

Abstract: The critical temperature, T c, for all presently known superconductors does not exceed 20°K. This fact obviously limits the range of applications of superconductivity in technology in a very fundamental way. On the whole, the reason why the value of T c for ‘ordinary’ superconductors should not exceed 20–40 °K is fairly well understood on the basis of the existing theory of superconductivity. At the same time, there apparently could exist high temperature superconductors for which the temperature T c would reach hundreds of degrees, or at least liquid air temperature. Possible means of producing high temperature superconductors are considered in this article. Special attention is paid to what can be called the exciton mechanism of superconductivity.

The processing and properties of bulk (re)bco high temperature superconductors: current status and future perspectives

Abstract: Bulk (RE)-Ba-Cu-O [(RE)BCO] cuprate HTS have been developed steadily towards a wide range of sustainable engineering and technological applications since their discovery in 1986 based primarily on their unique potential to trap very large magnetic fields (>5 T) at temperatures that are accessible potentially by thermo-electric cooling techniques. Trapped fields of ∼10 T at the surface of individual (RE)BCO bulk single grains and in excess of 17 T in a reinforced two-sample stack are now being achieved reliably. This paper reviews the current state of the art of the processing of large, single grain (RE)BCO bulk superconductors required to trap fields of this magnitude, and specifically via two advanced fabrication approaches; the traditional TSMG process and the more recently developed TSIG technique. The focus of the review is on optimising the critical processing parameters to achieve high-quality, high performance single grain (RE)BCO bulk superconductors specifically for high-field applications. The review also summarises recent advances in processing, such as the integration of the so-called buffer technique into the TSMG and TSIG processing methodologies to achieve improved reliability in single grain growth with a success rate exceeding 90%, the development of a Mg-doped NdBCO generic seed crystal for the successful growth of all rare-earth and light-rare earth based bulk superconductors [(RE)BCO and (LRE)BCO] and the introduction of nano-size stable, non-superconducting phase(s) to the bulk microstructure to improve the intrinsic flux pinning strength of the material, and hence trapped magnetic field. Details of the two-step buffer-aided TSIG technique developed recently that yields dense, near-net shaped, high performance (RE)BCO bulk superconductors with improved superconducting and mechanical properties are also presented. Suitable sample-seed configurations for effective multi-seeding are discussed, which enables the production of high aspect ratio, bar-shaped (RE)BCO quasi-single grains that exhibit improved levitation forces required in Maglev-based applications, for example, are discussed. The electrical, mechanical, microstructural and magnetic properties (including those achieved from a pulsed-field magnetisation approach) of the different (RE)BCO systems are presented and the relevant correlation in properties and performance highlighted, accordingly. Finally, a brief summary of existing applications and prospects for near-future exploitation of these remarkable, technologically important materials, and particularly in the medical and pharma-industries, is provided.

Electronic band structure of ferro-pnictide superconductors from ARPES experiment

Abstract: ARPES experiments on iron based superconductors show that the differences between the measured and calculated electronic band structures look insignificant but can be crucial for understanding of the mechanism of high temperature superconductivity. Here we focus on those differences for 111 and 122 compounds and discuss the observed correlation of the experimental band structure with the superconductivity.