Study Of High Temperature Superconductors Research Articles

High-temperature 63,65Cu NQR and NMR study of the high- temperature superconductor La 2- xSr xCuO 4 (0⩽x⩽0.15)

The nature of strong correlation between carriers and its relation to the mechanism of superconductivity have been among the central issues in the study of high-temperature superconductors. Recently, we succeeded in observing 63,65Cu NQR and NMR in the paramagnetic state of La 2 CuO 4, and antiferromagnetic ( T N ≏ 310 K) parent material of the high- T c superconductor La 1.85Sr 0.15CuO 4 ( T c ≏ 38 K). This enabled us to investigate the dependence of low-frequency Cu spin fluctuations on hole doping for the entire concentration range between the undoped insulating phase ( x = 0) and the maximum T c phase ( x = 0.15) and to test scaling theories.

Static Magnetic and Electron Paramagnetic Resonance Studies of High Temperature Superconductors and Related Compounds

Static Magnetic and Electron Paramagnetic Resonance Studies of High Temperature Superconductors and Related Compounds

Progress in the study of high-temperature superconductors

Progress in the study of high-temperature superconductors

NMR studies of high temperature superconductors

Results of NMR experiments mostly in YBa 2Cu 4O 7−δ are reviewed. The normal state data revealed two important aspects of the magnetic properties, namely, the temperature dependent antiferromagnetic Cu spin correlations and the spin gap behavior, the latter being observed in the reduced oxygen material. These features appear to be the general properties of many high T c cuprates. The Cu nuclear relaxation behavior in the superconducting state show some anomalous feature which remains to be explained.

Study of high-temperature superconductors by IBA methods

The ion-induced electron emission (IIEE) technique to study the high- T c superconductor of the Y 1Ba 2Cu 3 O 7 − x type was used. The temperature dependence of the IIEE intensity I( T) within the range of 77–300 K was measured. The change of the shape of the I( T) curve at the point 140 K was observed. The ion-induced photon emission technique (IIPE) to study the same high-temperature superconductor was also used. The temperature dependence of the intensity of some emission lines (BaI — 455.5 nm, CuI — 324.7 nm, YI — 467.4 nm) was measured. No anomaly at the point 140 K was observed. The nonmonotonic dependence of the IIEE intensity on the target temperature and the behaviour of the temperature dependence of the IIPE intensity are discussed.

High temperature superconductivity under pressure

Abstract This review is a summary of the work concerned with the pressure studies of high temperature superconductors (HTSC) held in the LOW Temperature Department of the IHPP since the last Conference in Paderborn (July, 1989).

Developments in the studies of high temperature superconductors

Developments in the studies of high temperature superconductors

Correlated Pair‐Transfer Mechanism for High Temperature Superconductivity. The Case of YBa2Cu3O6+x

AbstractA theoretical study of high temperature superconductivity in the system YBa2Cu3O6+x is made using the correlated pair transfer mechanism suggested recently. The mechanism involves the role of electron pairs in the spin singlet state of species \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm X}^{\uparrow \downarrow } (= {\rm Cu}^{{\rm 1 + }},{\rm O}_{\rm 2}^{{\rm 2 - }} {\rm, or O}^{{\rm 2 - }} {\rm)} $\end{document} and their virtual excited state X0(Cu3+, O, or O0) in the pairing interaction of quasiholes. The two states of these species can be likened to a two‐level Bose system. The strength of the interaction depends on the hole and species concentration. The expression for the transition temperature is a combination of phononic and the electronic mechanism and the calculated trend as a function of hole concentration (in effect excess O−) is in agreement with the observed trend. The mechanism is applicable to other oxide systems where such variable species can exist (e. g. Bi3+, Bi5+ or Tl1+, Tl3+, etc.). The theory has electron and hole symmetry, therefore it can also be applied to n‐type high temperature superconductors.

Book reviews

Abstract Abstract Electronic and Photonic Applications of Polymers. Edited by M. J. Bowden and S. R. Turner. (Washington: American Chemical Society, 1988.) [Pp. xiv + 353 + subject and author index.] Price US $94·95, hard cover. Tritium and Helium-3 in Metals. By R. Lasser. (Berlin, Heidelberg, New York: Springer-Verlag.) [Pp.ix + 151 + subject index.] Price DM98·00, hard cover. Microelectronics Processing. Edited by D. W. Hess and K. F. Jensen. (Washington: American Chemical Society, 1989.) [Pp. xiv + subject and author index.] Price US$59·95, hard cover. Introduction to the Mathematics of Quasicrystals. Edited by M. V. Jaric. (Boston, San Diego, New York: Academic Press, 1989.) [Pp. x +223 + subject index.] Price US $59·50, hard cover. Optical Nonlinearities and Instabilities in Semiconductors. Edited by H. Hung. (Boston, San Diego, New York Academic Press, 1988.) [Pp. x + 434 + subject index.] Price £45·00, hard cover. Solid State Physics. Volume 42. Edited by H. Ehrenreich and D. Turnbull. (Boston, San Diego, New York: Academic Press, 1989.) [Pp. ix + 402 + subject and author indexes.] Price £19·00, soft cover; £43·50, casebound. Strong Correlation and Superconductivity. Edited by H. Fukuyama, S. Maekawa and A. P. Malozemoff. (Berlin, Heidelberg, New York: Springer-Verlag, 1989.) [Pp.xii + 394 + author index.] Price DM 108·00, hard cover. The Principles and Practice of Electron Microscopy. By I. M. Watt. (Cambridge, New York, Port Chester: Cambridge University Press, 1989.) [Pp. viii + 297 + subject index.] Price £20·00, soft cover. (Amended paperback edition, hardback edition first published 1985.) The Emperor's New Mind. By R. Penrose. (Oxford, New York, Melbourne: Oxford University Press, 1989.) [Pp. xiii + 466 + subject index.] Price £20·00, hard cover. The Supercontinuum Laser Source. Edited by R. R. Alfano. (Berlin, Heidelberg, New York: Springer-Verlag, 1989.) [Pp. xiv + 458 + subject index.] Price DM 164·00. Vibronic Processes in Inorganic Chemistry. Edited by C. D. Flint. (Dordrecht, Boston, London: Kluwer Academic Publishers, 1989.) [Pp. vii + 391 + subject index.] Price £69·00/US $99·00, hard cover. (Proceedings of a NATO Advanced Study Institute held in Riva del Sole, Italy, 1988. Seventeen contributions.) The Art of Electronics. Second Edition and Student Manual. By P. Horowitz and W. Hill. (Cambridge, New York, Melbourne: Cambridge University Press, 1989.) [Pp. xxii + 1100 + subject index.] Price £29·95/US $49·50, hard cover. Price of Student Manual £12·50, soft cover. Studies of High Temperature Superconductors. Volume 3. Edited by A. Narlikar. (Commack: Nova Science Publishers, 1989.) [Pp. xvii + 406 + subject index.] Price US$87·00, hard cover. (Fifteen contributions.)

Ion beam irradiation studies of high temperature superconductors

We review two aspects of irradiation effects in high temperature superconductors (HTSC). First, irradiation does not just lead to random disordering of these materials. Intergranular couplings, nonstoichiometric and/or locally disordered zones, incompletely occupied sublattice planes and so on are all particularly sensitive to ion beam interactions, as shown by both structural and conduction properties. Secondly, on a more microscopic scale, controlled disordering of the HTSC by ion beam irradiation allows experiments that probe the basic mechanisms of transport and superconductivity in the HTSC. Specifically, we present a quantitative analysis of the irradiation-induced degradation of the superconducting critical temperature.

Current Trends in Studies of High Temperature Superconductors

Current Trends in Studies of High Temperature Superconductors

High resolution-angle resolved photoemission studies of high temperature superconductors

Recent photoemission studies of Y 123 and Bi 2212 performed with high energy and angular resolution have provided detailed information on the nature of the states near the Fermi level. Measurements of the superconducting gap, band dispersion, and the density of states near the Fermi level in the normal state all support a Fermi liquid description of these materials.

Book Review: Studies of High Temperature Superconductors. Volume 1. Edited by Anant Narlikar

Angewandte Chemie International Edition in EnglishVolume 28, Issue 11 p. 1592-1593 Book Review Book Review: Studies of High Temperature Superconductors. Volume 1. Edited by Anant Narlikar Herbert Jaeger, Herbert Jaeger Max-Planck-Institut für Metallforschung, Heisenbergstrasse 5, 7000 Stuttgart 80 (FRG)Search for more papers by this author Herbert Jaeger, Herbert Jaeger Max-Planck-Institut für Metallforschung, Heisenbergstrasse 5, 7000 Stuttgart 80 (FRG)Search for more papers by this author First published: November 1989 https://doi.org/10.1002/anie.198915922AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URLThe site is currently under maintenance and this functionality is not available right now. Please try later. Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume28, Issue11November 1989Pages 1592-1593 RelatedInformation

ON THE ELECTRODYNAMICS OF JOSEPHSON EFFECT IN ANISOTROPIC SUPERCONDUCTORS

Specificities of Josephson effect electrodynamics in anisotropic superconductors are of considerable interest for the study of high temperature superconductors with strongly anisotropic layered structure. In this paper the authors give the calculation for the tunnel Josephson contact of an isolated vortex, the law of dispersion of its low-amplitude oscillations, the critical field H/sub cl/ for the penetration of magnetic flux, and the maximum current across a rectangular contact.

Field and Temperature Dependent Suspension Studies of High Temperature Superconductors

AbstractWe have employed a novel variable-temperature, variable-field/field-gradient cryogenic levitometer, previously used in levitation experiments, to study the suspension properties of the thallium-based high temperature superconductors. Our results are compared and contrasted with the levitation studies and the singular features of the suspension properties are noted.

Crystal Growth of High Temperature Superconductors

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.

The anisotropic superconductivity of RBa 2Cu 3O 7−x (R : Y, Gd and Ho) single crystals

Our study of high temperature superconductivity in RBa 2Cu 3O 7 − x (R:Y, Gd and Ho) using single crystal samples is reviewed with emphases on the anisotropic transport properties in the superconducting phase as well as the normal phase. Recent transport results obtained by use of a new technique for attaching a number of electrical leads on a small single crystal are also presented.

Infrared studies of high temperature superconductors

Infrared measurements have been used both to study the superconducting energy gap and the normal state electronic character of the high T c oxide superconductors. While the question of the existence of a gap is not yet completely resolved, we find strong evidence for a very large energy gap, 2†≌8kT c, in the a-b plane response of crystal Y 1Ba 2Cu 3O 7. Simple calculations also support the assertion that the much smaller gap values, 2†≾4kT c, inferred from polycrystalline data are associated with the c-axis response. The relationship between infrared, tunnelling and NQR measurements of the energy gap is not yet clear. The normal state conductivity, which is obtained from a Kramers-Kronig transform of the reflectivity, remains controversial. We find that the normal state conductivity above ≈ 1000cm -1 is primarily Durde-like with modest interband contributions beginning at about 6000cm -1. The area of our Drude curve corresponds to a density of 5×10 21 cm-3 assuming a mass of 1 at high frequency. Below 1000cm -1 we suggest that a frequency dependent scattering rate will be required to obtain an appropriate correspondence between the infrared conductivity and the strongly temperature dependent d.c. conductivity. Reliably obtaining this frequency dependence should substantially improve our understanding of transport in the normal state.

NMR studies of high temperature superconductors

63Cu NMR measurements of the YBa 2Cu 3O 7−δ (δ = 0 to 0.8) compound in 8.5 and 11.7 Tesla magnetic fields show that both planes and chains are metallic and superconductive with a complicated gap structure. The chains show partial octahedral oxygen ordering at high temperatures and magnetic ordering in the tetragonal phase.