Home About us Contact | |||
High-temperature Superconductivity (high-temperature + superconductivity)
Selected AbstractsCommercial Exploration of High-Temperature SuperconductivityLASER TECHNIK JOURNAL, Issue 4 2010Excimer Lasers Enable Novel Coated Superconductor Cylinders Superconductivity, which is the condition in which the electrical resistance of a material drops to zero, was discovered nearly 100 years ago. Since that time, large superconducting magnets such as those used in magnetic resonance imaging (MRI), nuclear magnetic resonance (NMR) and big physics experiments have been developed and can now be regarded as being commercial products extending our capabilities in medicine and science. Yet many industrial applications of high temperature superconductivity (HTS) are on the horizon waiting to enter the marketplace. Currently, numerous manufacturers are working on improving and upscaling HTS materials, which operate at liquid nitrogen temperatures, and the most promising configuration for these materials is in the form of long tapes also known as coated conductors. These coated conductors are wound into coils in order to produce electrical components such as motors, magnets, transformers etc. Depending on the component to be made, there is an alternative to fabricating long unit lengths of superconducting tape, and in forming stable robust windings utilizing them. Now, a new technique has been developed which is using pulsed laser deposition (PLD) to deposit a series of layers of superconducting material directly on to the surface of a cylinder and patterning them into coils. This configuration provides a very direct route for the production of components that conventionally involve winding processes. This article explores how coated conductor cylinders can be produced utilizing this technique and explains why industriallyproven excimers represent the optimum choice of laser source for this emergingtechnology. [source] Very High Critical Field and Superior Jc -Field Performance in NdFeAsO0.82F0.18 with Tc of 51 K,ADVANCED MATERIALS, Issue 2 2009Xiaolin Wang A new family of oxypnictide superconductors, LaFeAsO0.89F0.11, brings new impetus to the field of high-temperature superconductivity. In this work, we show that the upper critical field values Hc2 (48 K) = 13 T and Hc2(0) can exceed 80,230 T in a high-pressure-fabricated NdO0.82F0.18FeAs bulk sample with Tc of 51 K. We also demonstrate the superior performance of supercurrent density in fields for this new superconductor. [source] Vibronic polarons: Self-trapping, local rotation, and band featuresINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 4 2002A. G. Andreev Abstract We revisit basic theoretical concepts of local and itinerant vibronic polarons in crystals. The following results may be regarded as novel: (1) The electron self-trapping rate to a small polaron is calculated via the reaction rate method; subsequently, self-trapped on-center small polarons relax to an off-center vibronic polaron state. (2) The general vibronic Hamiltonian is redefined so as to incorporate both local and itinerant behavior and pairing into bipolarons or Cooper pairs. (3) The planar rotation and diametral tunneling of an off-center polaron around and across its centrosymmetrical site are dealt with to adiabatic approximation. (4) Variational calculations are made for vibronic polarons itinerant along 1-D chains by means of a two-band extension of Merrifield's ansatz. This investigation of vibronic polarons is undertaken in view of their presumed role in high-temperature superconductivity and colossal magnetoresistance. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002 [source] Interplay of magnetism and superconductivityPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 11 2006M. Akhavan Abstract After about two decades of intense research since the discovery of high-temperature superconductivity (HTSC) in cuprates, although many aspects of the physics and chemistry of these cuprate superconductors are now well understood, the underlying pairing mechanism remains elusive. Magnetism and superconductivity are usually thought as incompatible, but in number of special materials including HTSCs these two mutually excluding mechanisms are found to coexist. The presence in a system of superconductivity and magnetism, gives rise to a large number of interesting phenomenon. This article provides perspective on recent developments and their implications for our understanding of the interplay between magnetism and superconductivity in new materials. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Homes relation in the attractive Hubbard model in d = ,PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 1 2006M. Bak Abstract Lack of the recognized theory of high-temperature superconductivity (HTS) has led to an intense experimental and theoretical search for some universal relationships, which might unravel the physics behind the HTS. One of the most known is so called Uemura relation, ,s(0) , Tc, where ,s is superfluid density and Tc is the superconducting transition temperature. Recently Homes et al. [Nature 430, 539 (2004)] reported a new universal scaling relation, ,s , ,dc(Tc) · Tc, where ,dc(T ) is dc conductivity. In the present paper Homes relation is investigated theoretically in the limit of infinite dimensions in the second order perturbation theory. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] |