scholarly journals EXPERIMENTAL STUDY OF THE SUPERCONDUCTING MICROSTRIP ANTENNA AS A PROTECTIVE DEVICE OF THE RECEIVER FROM ELECTROMAGNETIC DAMAGE

2017 ◽  
Vol 5 ◽  
pp. 73-88
Author(s):  
Oleksandr Fyk ◽  
Dmutro Kucher ◽  
Roman Gonchar
Keyword(s):  
High Temperature ◽  
Superconducting State ◽  
Microstrip Antenna ◽  
High Temperature Superconductivity ◽  
High Temperature Superconductors ◽  
Experimental Studies ◽  
Analytical Form ◽  
Frequency Characteristics ◽  
Superconducting Film ◽  
Protective Device

The paper presents the results of experimental studies of a superconducting protective antenna, which consists of a high-temperature film deposited by a magnetron or a laser beam on a substrate. The work is carried out: - analysis of the selection criteria for the substrate type (Al2O3, Y2O3, SrTiO3, MgO) and the method for depositing a high-temperature superconducting film (HTSF) on its surface – YBaCuO - analysis of the methods of making contacts, which allow to reduce losses when passing a signal from the superconducting microstrip antenna to the waveguide path. The aim of this article is determination of the parameters of a prototype sample of a microstrip antenna device made from HTSF: transient characteristics of high-temperature superconductors, HTSF impulsive characteristics, recovery time of the superconducting state after the action of a powerful pulse on the protective device, the amplitude-frequency characteristics of the protective device in the superconducting state. This will allow to evaluate the possibility of using a microstrip antenna device made from high-temperature superconductors to protect the receiving systems from electromagnetic damage. The absence of a unified theory of high-temperature superconductivity leads to the need to select an analytical form of the functions of the amplitude-frequency characteristics of superconducting protection, and for this mathematical models are used in the programs "APPROX", "MathCAD14.0". The reliability of the obtained results of mathematical modeling of the processes of protection and recovery of the superconducting state after electromagnetic shock are confirmed in the course of experimental studies (an error of 0.15%).

scholarly journals Square Lattice Iridates

2019 ◽  
Vol 10 (1) ◽  
pp. 315-336 ◽  
Author(s):  
Joel Bertinshaw ◽  
Y.K. Kim ◽  
Giniyat Khaliullin ◽  
B.J. Kim
Keyword(s):  
High Temperature ◽  
High Temperature Superconductivity ◽  
High Temperature Superconductors ◽  
Single Layer ◽  
Square Lattice ◽  
Spin Orbit Coupling ◽  
Fermi Arcs ◽  
Firm Evidence ◽  
Energy Physics ◽  
Strong Spin

Over the past few years, Sr2IrO4, a single-layer member of the Ruddlesden–Popper series iridates, has received much attention as a close analog of cuprate high-temperature superconductors. Although there is not yet firm evidence for superconductivity, a remarkable range of cuprate phenomenology has been reproduced in electron- and hole-doped iridates including pseudogaps, Fermi arcs, and d-wave gaps. Furthermore, many symmetry-breaking orders reminiscent of those decorating the cuprate phase diagram have been reported using various experimental probes. We discuss how the electronic structures of Sr2IrO4 through strong spin-orbit coupling leads to the low-energy physics that had long been unique to cuprates, what the similarities and differences between cuprates and iridates are, and how these advance the field of high-temperature superconductivity by isolating essential ingredients of superconductivity from a rich array of phenomena that surround it. Finally, we comment on the prospect of finding a new high-temperature superconductor based on the iridate series.

scholarly journals SPECTRAL ANOMALY AND HIGH TEMPERATURE SUPERCONDUCTORS

1996 ◽  
Vol 10 (07) ◽  
pp. 805-845 ◽  
Author(s):  
LAN YIN ◽  
SUDIP CHAKRAVARTY
Keyword(s):  
High Temperature ◽  
Spectral Function ◽  
Superconducting State ◽  
Fermi Liquid ◽  
Cuprate Superconductors ◽  
High Temperature Superconductors ◽  
Universality Class ◽  
Scaling Relation ◽  
Critical System ◽  
Spectral Anomaly

Spectral anomaly for interacting fermions is characterized by the spectral function A ([k − k F ], ω) satisfying the scaling relation A (Λy1 [k − k F ], Λy2 ω) =ΛyA A ([k − k F ], ω), where y1, y2, and yA are the exponents defining the universality class. For a Fermi liquid y1 = 1, y2 = 1, yA = −1; all other values of the exponents are termed anomalous. In this paper, an example for which y1 = 1, y2 = 1, but yA = α − 1 is considered in detail. Attractive interaction added to such a critical system leads to a novel superconducting state, which is explored and its relevance to high temperature cuprate superconductors is discussed.

Electron-Doped High Tc Superconductors

MRS Bulletin ◽  
1990 ◽  
Vol 15 (6) ◽  
pp. 60-67 ◽  
Author(s):  
M. Brian Maple
Keyword(s):  
High Temperature ◽  
High Temperature Superconductivity ◽  
High Temperature Superconductors ◽  
Building Blocks ◽  
The United States ◽  
Charge Carriers ◽  
Critical Temperatures ◽  
High Tc ◽  
Prevailing View ◽  
Identical Crystal

Since the discovery of high temperature superconductivity in layered copper-oxide compounds in the latter part of 1986, an enormous amount of research has been carried out on these remarkable materials. Prior to 1989, the prevailing view was that the charge carriers responsible for superconductivity in these materials were holes that move through conducting CuO2 planes. The CuO2 planes are the basic building blocks of the crystal structures of all the presently known oxides with superconducting critical temperatures Tc greater than ~30 K. Recently, new superconducting materials have been discovered in Japan and the United States in which the charge carriers involved in the superconductivity appear to be electrons, rather than holes, that reside within the conducting CuO2 planes. These findings could have important implications regarding viable theories of high temperature superconductivity as well as strategies for finding new high temperature superconductors.The new electron-doped materials have the chemical formula Ln2-xMxCuO4-y and exhibit superconductivity with superconducting critical temperatures Tc as high as ~25 K for x ≍ 0.15 and y ≍ 0.02. Superconductivity has been discovered for M = Ce and Ln = Pr, Nd, Sm, and Eu, and for M = Th and Ln = Pr, Nd, and Sm. A related compound with the identical crystal structure, Nd2CuO4-x-y Fx, has also been found to display superconductivity withTc ≍ 25 K. Recently, it has been observed that superconductivity with Tc ≍ 25 K can even be induced in nonsuperconducting Nd2-xCexCuO4-y compounds by substituting Ga or In for Cu. Thus, it appears that the CuO2 planes can be doped with electrons, rendering the Ln2CuO4-y parent compounds metallic and superconducting, by substituting electron donor elements at sites within, as well as outside, the CuO2 planes; i.e., by substituting (1) Ce4+ or Th4+ ions for Ln3+ ions; (2) F1- ions for O2- ions; and (3) Ga3+ or In3+ ions for Cu2+ ions.

EFFECTIVE THEORY FOR HIGH-TEMPERATURE SUPERCONDUCTIVITY BASED ON DUALITY AT S = 1/2 ANTIFERROMAGNETIC HEISENBERG MODEL

2005 ◽  
Vol 19 (12) ◽  
pp. 571-579 ◽  
Author(s):  
TAKAO MORINARI
Keyword(s):  
High Temperature ◽  
Heisenberg Model ◽  
High Temperature Superconductivity ◽  
High Temperature Superconductors ◽  
Parent Compound ◽  
High Energy ◽  
Field Application ◽  
Effective Theory ◽  
Dirac Fermions ◽  
Antiferromagnetic Heisenberg Model

It is argued that in two-dimension duality connects the CP1 representation of the S = 1/2 antiferromagnetic Heisenberg model with the Schwinger model in which Dirac fermions are interact via a U(1) gauge field. Application of this duality to underdoped high-temperature superconductors suggests that the high-energy fermionic excitation at the Mott insulating parent compound turns out to be a low-lying excitation in the spin disordered regime. A picture for high-temperature superconductivity is proposed.

Crystal Growth of High Temperature Superconductors

MRS Bulletin ◽  
1988 ◽  
Vol 13 (10) ◽  
pp. 56-61 ◽  
Author(s):  
H.J. Scheel ◽  
F. Licci
Keyword(s):  
High Temperature ◽  
Critical Current Density ◽  
Single Crystals ◽  
Critical Current ◽  
Current Density ◽  
Large Scale ◽  
High Temperature Superconductivity ◽  
High Temperature Superconductors ◽  
Superconducting Transition ◽  
Theoretical Understanding

The discovery of high temperature superconductivity (HTSC) in oxide compounds has confronted materials scientists with many challenging problems. These include the preparation of ceramic samples with critical current density of about 106 A/cm2 at 77 K and sufficient mechanical strength for large-scale electrotechnical and magnetic applications and the preparation of epitaxial thin films of high structural perfection for electronic devices.The main interest in the growth of single crystals is for the study of physical phenomena, which will help achieve a theoretical understanding of HTSC. Theorists still do not agree on the fundamental mechanisms of HTSC, and there is a need for good data on relatively defect-free materials in order to test the many models. In addition, the study of the role of defects like twins, grain boundaries, and dislocations in single crystals is important for understanding such parameters as the critical current density. The study of HTSC with single crystals is also expected to be helpful for finding optimum materials for the various applications and hopefully achieving higher values of the superconducting transition temperature Tc than the current maximum of about 125 K. It seems unlikely at present that single crystals will be used in commercial devices, but this possibility cannot be ruled out as crystal size and quality improve.

PAIRING STATE AND HIGH TEMPERATURE SUPERCONDUCTIVITY OF SEMI-LOCALIZED 2D ELECTRON SYSTEM WITH CIRCULAR MOLECULAR ORBITS

2002 ◽  
Vol 16 (10n11) ◽  
pp. 351-362 ◽  
Author(s):  
MASANORI SUGAHARA ◽  
NIKOLAI N. BOGOLUBOV
Keyword(s):  
High Temperature ◽  
Transition Temperature ◽  
Upper Bound ◽  
High Temperature Superconductivity ◽  
High Temperature Superconductors ◽  
Electron System ◽  
Circular Orbits ◽  
New Model ◽  
Pairing State ◽  
The Stability

Recently, new types of high temperature superconductors have been found which are characterized by the existence of circular molecular orbits in each unit site of 2D s/p electron system. In view of the characteristic, a new model of superconductivity is studied based on the stability of the correlated state of electrons in the 2D interconnection of circular orbits. This model gives an estimation of the upper bound of superfluidity transition temperature: T c ~ 130-400 K for fcc C 60, and T c ~ 110-340 K for hole-doped MgB 2.

Crystal Growth, Structure, and Incoherent Metallic Behaviour of FeCrAs

2011 ◽  
Vol 170 ◽  
pp. 276-281 ◽  
Author(s):  
Wen Long Wu ◽  
Alix McCollam ◽  
Ian P. Swainson ◽  
Stephen R. Julian
Keyword(s):  
High Temperature ◽  
High Temperature Superconductivity ◽  
High Temperature Superconductors ◽  
Magnetic Hysteresis ◽  
Freezing Temperature ◽  
Growth Structure ◽  
Preparation Conditions ◽  
Scattering Rate ◽  
Spin Freezing ◽  
Low Levels

There is growing interest in a possible connection between incoherent metallic conduction and high temperature superconductivity, that is exemplified by the behaviour of the parent compounds of the new iron-pnictide high-temperature superconductors. We have recently discovered very incoherent behaviour in the non-superconducting arsenide, FeCrAs. This material shows a non-metallic resistivity that rises with decreasing temperature without saturation or a gap, over three decades of temperature, from 80 mK to 800 K. We briefly review this behaviour, and address the question of disorder: how to test for the presence of disorder in a system where the scattering rate inferred from the resistivity is highly abnormal, and how to produce single crystals with low levels of disorder. Our discussion will focus on magnetic properties. FeCrAs is a partly frustrated magnetic system with a Nèel temperature TN that depends on sample quality, a sample-dependent spin freezing temperature TF < TN, and magnetic hysteresis that depends strongly on preparation conditions due to ferromagnetic minority phases in disordered samples.

High-Temperature Superconductors 1992: Bringing the Materials Under Control

MRS Bulletin ◽  
1992 ◽  
Vol 17 (8) ◽  
pp. 16-19 ◽  
Author(s):  
David C. Larbalestier
Keyword(s):  
High Temperature ◽  
High Temperature Superconductivity ◽  
High Temperature Superconductors ◽  
Research Society ◽  
Superconducting Phase ◽  
Bscco System ◽  
University Of Houston ◽  
Materials Research ◽  
Scientists And Engineers ◽  
Phase Sample

As I write, it is about six years since Bednorz and Müller sent off their amazing paper reporting superconductivity at about 30 K for a mixed phase sample in the La-Ba-Cu-O system. After an incubation period of a few months, during which only a handful of people paid any attention, the community suddenly woke up (literally overnight) to the realization that the discovery was genuine, when Kitazawa (Tokyo University) and Chu (University of Houston) confirmed the result at the 1986 Fall Meeting of the Materials Research Society. No need to repeat the stories of the next frantic couple of years: the Nobel Prize for the discovery, the tantalizing prospect of another prize for understanding the superconducting mechanism, the almost limitless prospects of new superconducting technologies which appeared in article after article, designed not just for scientists and engineers, but for the general public at large. Now, six years later, perhaps some perspective on the high-temperature superconductivity discoveries is possible.At the fundamental science level, the discoveries have indeed been spectacular. Many layered structures based on the CuO2 sheets have been discovered. The first advance was the Tokyo group's discovery of the structure and composition of the superconducting phase La2-xBaxCuO4-δ, where x is optimally about 0.15. Then came the Alabama/Houston discovery of superconductivity at 92 K in YBa2Cu3O7-δ, followed rather quickly by the discoveries of 110 K superconductivity in the Bi-Sr-Ca-Cu-O (BSCCO) system at Tsukuba and then 125 K in the Tl-Ba-Ca-Cu-O (TBCCO) system by the Arkansas group.

scholarly journals Unusual symmetries of the order parameter in cuprates

2020 ◽  
Vol 2 (4) ◽  
pp. 207-212
Author(s):  
Tran Van Luong ◽  
Nguyen Thi Ngoc Nu
Keyword(s):  
High Temperature ◽  
Order Parameter ◽  
Cuprate Superconductors ◽  
High Temperature Superconductivity ◽  
Spin Fluctuation ◽  
High Temperature Superconductors ◽  
Coulomb Repulsion ◽  
Bcs Theory ◽  
S Wave ◽  
Wave Symmetry

The BCS superconducting theory, introduced by J. Bardeen, L. Cooper and R. Schriffer in 1957, succeeded in describing and satis-factorily explaining the nature of superconductivity for low-temperature superconductors. However, the BCS theory cannot explain the properties of high-temperature superconductors, discovered by J. G. Bednorz and K. A. Müller in 1986. Although scientists have found a lot of new superconductors and their transition temperatures are constantly increasing, most high-temperature superconductors are found by experiment and so far no theory can fully explain their properties. Many previous studies have suggested that the order parameter in high-temperature copper-based superconductors (cuprate superconductors - cuprates) is in the form of d-wave symmetry, but recent results show that the order parameter has an extended s-wave symmetry (extended s wave). Studying the symmetric forms of order parameters in cuprate can contribute to understanding the nature of high-temperature superconductivity. In this article, the authors present an overview of the development of high-temperature supercon-ductors over the past 30 years and explains unusual symmetries of the order parameter in copper-based superconductors. The com-petition of three coupling mechanisms of electrons in cuprates (the mechanism of coupling through coulomb repulsion, electron-phonon mechanism and spin-fluctuation mechanism) affects the unusual symmetry of the order parameter. The solution of the self-consistency equation in simple cases has been found and the ability to move the phase within the superconducting state has been shown.

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