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Topic: Cuprate

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In the News (Tue 19 Mar 19)

Similar to the hole-doped cuprates, the electron-doped cuprates possess a strongly temperature-dependent Hall coefficient.
For hole-doped cuprates it has been shown that the superconducting order parameter (gap) has a d-wave symmetry, quite different that most conventional, low-Tc superconductors which have a s-wave symmetry.
This question is difficult to answer in the hole-doped cuprates because it would take an enormous magnetic field to suppress the superconductivity at T=0 and reach the normal state.
www.csr.umd.edu /csrpage/research/superconductingmat/cuprates.htm   (431 words)

One of the most controversial topics in the field of superconductivity in the last decade has been the symmetry of the Cooper pairing in the high critical temperature cuprate superconductors.
In this geometry, any closed ring of superconducting material around the central point is "frustrated" for a d-wave superconductor, and spontaneously generates magnetic fields with half of the conventional total superconducting flux quantum at the center (tricrystal) point.
The cuprate superconductors are composed of planes of CuO
www.research.ibm.com /halfvortex   (759 words)

 Unusual Ceramics Could Expand Possibilities For Superconductors
Scientists have been arguing for years whether cuprates exhibit one type of superconductivity, called d-wave, or another type, called s-wave, explained Thomas Lemberger, professor of physics.
As the researchers pushed the cerium content of the cuprates to the limit, the magnetic field measurements suggested that the electrons had changed their formation from d-wave to s-wave.
Lemberger said the scientific controversy surrounding the nature of superconductivity in cuprates will come to a head this summer, as researchers gather in Taiwan to debate which of the two "personalities," d-wave or s-wave, is the true state of the material.
researchnews.osu.edu /archive/cuprate.htm   (707 words)

 Oxford Physics - Oxford Physics - Condensed Matter Physics - Superconductors   (Site not responding. Last check: 2007-10-08)
Much of the work is motivated by the desire to understand the mechanism of superconductivity in unconventional systems, such as the layered cuprate high-Tc superconductors.
A wide range of cuprate and non-cuprate crystals are grown by flux techniques from solution at temperatures up to 1400 C. Alloying with suitable species to produce overdoped or underdoped material allows the superconducting properties to be controlled.
The reason for this intense interest in organic molecular metals is that they form a uniquely flexible system for the study of superconductivity, magnetism and the effects of electron correlation.
www.physics.ox.ac.uk /CM/Superconductors.htm   (1681 words)

 The underdoped phase of cuprate superconductors (February 2000) - Physics World - PhysicsWeb
The origin of high-temperature superconductivity in cuprate materials is one of the biggest puzzles in physics, but the behaviour of these materials when they are not superconducting is an even bigger mystery.
Cuprates with superconducting transition temperatures as high as 130 K have been discovered, and the cuprate family of materials continues to be of immense theoretical and experimental interest.
The cuprates are antiferromagnets at low doping, so it is natural to propose that antiferromagnetic fluctuations are responsible for the pseudogap phase in the underdoped region (see Pines in further reading).
physicsweb.org /article/world/13/2/8   (3302 words)

 Current understanding of electronic structure and some difficulties with cuprate semiconductors
cuprate superconductors are reviewed from the perspective of electronic structures.
On the basis of Mott-Hubbard-type band splitting, the semiconductivity, antiferromagnetism, and metallic nature of the cuprate oxides are discussed as a function of the dopant concentration.
Finally, the complex nature of the Fermi surface is considered, and the importance of the involvement of both the O 2p and the lower Hubbard band is stressed.
domino.research.ibm.com /tchjr/journalindex.nsf/0b9bc46ed06cbac1852565e6006fe1a0/e75bf3c03c22078285256bfa0067fa71?OpenDocument   (110 words)

 Tuning magnetic and bond order in the cuprate superconductors
Given the picture of competing orders and quantum phase transitions in the cuprate superconductors (reviewed in S. Sachdev, Science 288, 475 (2000); cond-mat/0009456), it is natural to search for an external parameter which will tune systems across such transitions.
In strongly type-II superconductors like the cuprates, above a small lower critical field, a magnetic field perpendicular to the layers induces a triangular lattice of vortices: superconductivity is completely suppressed in the very small vortex cores, and these are surrounded by regions of superflow of Cooper pairs (see Figure 3 below).
Spin and charge order in the vortex lattice of the cuprates: experiment and theory, S. Sachdev, Developments in Mathematical and Experimental Physics, Volume B: Statistical Physics and Beyond, A. Macias, F. Uribe, and E. Diaz eds, Kluwer Academic, New York (2002); cond-mat/0203363.
qpt.physics.harvard.edu /superflow.html   (1817 words)

 "MOTTNESS" MIGHT HELP TO EXPLAIN CUPRATE BEHAVIOR.   (Site not responding. Last check: 2007-10-08)
One of the most studied materials in all of science, cuprates are layer cakes consisting of copper-oxygen planes alternating with planes in which other elements, such as strontium or lanthanum, are stocked in varying ratios.
Many scientists believe that one of the keys to understanding why the cuprates are such good superconductors in the cold regime is to learn why they are Mott insulators in the warm regime and how such physics manifests itself when they are doped.
One more oddity about the cuprates is the issue of "pseudogaps." In a superconductor, the energy required to break up a pair of electrons is termed the "energy gap." But in the cuprates, a partial gap still persists even when superconductivity is destroyed.
newton.ex.ac.uk /aip/glimpse.txt/physnews.645.2.html   (567 words)

 Scenario for high-temperature, cuprate superconductivity proposed
The BCS theory-- developed in 1957 by John Bardeen, Leon Cooper and John Schrieffer (all three researchers were at the U. of I. at that time)-- explains superconductivity at temperatures close to absolute zero, but has difficulty accounting for the higher temperatures that were later achieved with the cuprates.
Cooper-pair production in the cuprates, however, is probably not dependent upon the crystal lattice, Leggett said.
"My fundamental hypothesis is that the driving force leading to superconductivity in the cuprates is the saving of Coulomb energy in the regime of long wavelengths and midinfrared frequencies," Leggett said.
www.eurekalert.org /pub_releases/1999-09/UoIa-Sfhc-070999.php   (344 words)

The main result is that all members of the family have similar phase diagram (with T and doping on the axis).
Commonly known as the ‘pseudogap’ this phase it is a conductor but with properties much different from the properties of the usual conductors (generally Fermi liquids).
It is clear that the electron-phonon interaction that is responsible for the conventional SC is way to weak to do the same in the cuprates — the temperature is too high (this is one of the reasons for the surprise in 1986 — nobody was expecting such a high T
www.pha.jhu.edu /~vstanev1   (905 words)

 Dr. Neil Hyatt: publications.   (Site not responding. Last check: 2007-10-08)
The study of condensed matter under high pressure is important since dramatic changes in physical properties may be induced by compression of interatomic bond-lengths.
My principal interest in high pressure crystallography is the study of compressibility-structure relationships in cuprate superconductors using high pressure powder X-ray and neutron diffraction techniques.
The mercury based cuprate superconductors are characterised by a small excess of oxygen, I have recently shown, from a combined powder X-ray and neutron diffraction study of HgBa
www.homestead.com /solidsolutions/Projects.html   (388 words)

 Nature of Electronic Excitations in Cuprate Superconductors ^*   (Site not responding. Last check: 2007-10-08)
We reexamine the nature of the electronic continuum seen in cuprate superconductors and its redistribution at low temperatures to reveal "gap-like features." Electronic Raman scattering in cuprate superconductors has been conventionally discussed using a model developed for low temperature superconductors.
This picture is difficult to reconcile with large apparent values of 2 \Delta / kT_c from Raman data and with the observation of gaplike features in underdoped cuprates for T > T_c.
We present experimental results, including resonance Raman studies, suggesting that the two-magnon Raman spectra observed in the antiferromagnetic parent insulator persist in the superconducting materials and will discuss several implications of the hypothesis that the continuum and the gap-like features observed at low temperatures are related to the two-magnon spectrum.
flux.aps.org /meetings/BAPSMAR95/abs/SB_0101.html   (254 words)

 13C Kinetic Isotope Effects for the Addition of Lithium Dibutylcuprate to Cyclohexenone. Reductive Elimination is ...
However, the central evidence for the importance of electron transfer - the correlation of reactivity with reduction potential - is compromised because it is the energy of the transition state for the rate-limiting step that determines reactivity.
It is also clear that studies trying to understand or control the stereochemistry of cuprate conjugate additions should focus on the reductive-elimination step.
The mechanism of cuprate reactions is often thought to depend on cuprate structure, substrate, solvent, additives (e.g., TMSCl), and the detailed reaction conditions.
www.chem.tamu.edu /rgroup/singleton/cuprate.html   (1029 words)

 Swedish Superconductivity Consortium
Study fundamental properties of the thallium cuprates in the form of thin films and single crystals.
Tl cuprate films will be prepared on bicrystal and tricrystal STO substrates to probe the symmetry of the order parameter.
We synthesise cuprate superconductors and study the relation between structure and superconducting properties.
fy.chalmers.se /supra/project_groups/new_super00.html   (702 words)

 Cuprate Voodoo. In the Pipeline:
I was using a so-called "higher-order cuprate" reagent, which you make from copper cyanide and lithium reagents, and it worked just fine for me the first time out.
Somewhere in the older cuprate lit there is a footnote saying that some of the "HO" jobbies don't go if you use the std off-white septa, and the reddish-orange kind are crucial for success...
What I found was that cuprates generally do not form very well at -78C.
www.corante.com /pipeline/archives/2005/05/16/cuprate_voodoo.php   (948 words)

 The Theory of Superconductivity in the High-TC Cuprate Superconductors
The Theory of Superconductivity in the High-TC Cuprate Superconductors
This book is P. Anderson's long-awaited full presentation of his theory of high-T[subscript c] superconductivity in the cuprates.
The fundamental insight contained in the book is that the conditions for validity of the renormalized quasiparticle theory of metals ("Fermi Liquid Theory") are much more restrictive than had been thought, and are not satisfied in the CuO[subscript 2] planes of high-T[subscript c] materials (among, probably, many other examples).
www.angelfire.com /ca/kenlab/Super1.html   (361 words)

 Chen, Ching-Tzu (2006-05-19) Scanning tunneling spectroscopy studies of high-temperature cuprate superconductors. ...
The absence of the satellite features and pseudogap in tunneling spectra of electron-doped cuprates sharply contrasts with their general presence in hole-doped cuprates.
For instance, the coexistence of the pseudogap and superconducting spectra in hole-doped cuprates and the observations of the current- and field-induced pseudogap in electron-doped cuprates suggest that competing orders, manifested as the pseudogap, coexist with superconductivity in both types of cuprates.
Furthermore, by tuning the ratio of the density waves to superconductivity, the theoretical calculations reproduce the absence of pseudogap phenomena in electron-doped cuprates and the general presence of he pseudogap in hole-doped cuprates.
etd.caltech.edu /etd/available/etd-05222006-124257   (370 words)

 Figures: Structure of High Temperature Superconductors   (Site not responding. Last check: 2007-10-08)
Figure 1: (a) Perovskite Structure with B at origin (b) Perovskite Structure with A at origin (c) Stacking of perovskite unit cells.
Figure 6: Building blocks used to construct the structures of cuprate superconductors.
Figure 28: Schematic stacking sequences of high temperature superconducting cuprate phases.
scholes.alfred.edu /EandS/Pub/snyder/Text/htsc-str.html   (290 words)

 Emily Cuprate 1901 - present   (Site not responding. Last check: 2007-10-08)
She has been in hospital for bad flu, so we are celebrating her anniversary a little early.
As always, it will be in the Duck N Diner on 3rd, then the traditional dancing and singing on this joyous occasion.
This is Emily Cuprate when she was just 12 in Germany
www.freewebs.com /emilycuprate   (151 words)

 Innovations: Electric Motors with High Temperature Cuprate Superconductors in the Rotor
The benefits of using copper, with its excellent electrical conductivity, for the stator windings of an electric motor have been recognized for many years.
It has a Tc of 93K (-292 F, -180 C), which is higher than the boiling point of liquid nitrogen.
Liquid nitrogen is relatively inexpensive and much easier to handle than liquid helium, and this happy phenomenon allows the new copper-oxide, or cuprate superconductors, as they are sometimes called, to be considered for applications that were not viable with earlier superconductors.
www.copper.org /innovations/2000/06/electric-motors-cuprate-supercondutors.htm   (1730 words)

 The condensate fraction in high-Tc cuprate superconductors
cuprate superconductors, the nature and doping dependence of the condensate in such materials is still uncertain.
cuprate superconductors, closely follows the upper bound given by C.N. Yang's theorem for condensation within a single band.
The authors infer that the condensate transports negative charge in electron-doped and hole-doped cuprate layers, which rationalizes the experimental observation that the London moments of conventional superconducting metals and superconducting ceramics have the same sign.
stacks.iop.org /0953-8984/4/L563   (308 words)

 4PO1-60 to 4PO1-69
We shall present evidence that they are actually p-type, and that all high-temperature cuprate superconductors are p-type.
We propose a two-band model for extrinsic and intrinsic hole systems in cuprate superconductors that incorporates the long-range Coulomb interactions, which is an extension of a lattice Anderson model.
Therefore, the two-band model explains coexistence of superconductivity and antiferromagnetism in cuprates.
m2s-conf.uh.edu /abstracts/4PO1_7.html   (1567 words)

 Fu, Chu-Chen (2002-10-17) Spin-polarized quasiparticle transport in cuprate superconductors. ...
Fu, Chu-Chen (2002-10-17) Spin-polarized quasiparticle transport in cuprate superconductors.
The temperature dependence of the efficiency in the F-I-S samples is also in sharp contrast to that in the N-I-S samples, suggesting significant redistribution of quasiparticles in F-I-S due to the longer lifetime of spin-polarized quasiparticles.
The characteristic times estimated from our studies are suggestive of anisotropic spin relaxation processes, possibly with spin-orbit interaction dominating the c-axis spin transport and exchange interaction prevailing within the CuO2 planes.
etd.caltech.edu /etd/available/etd-10242002-021518   (245 words)

 Copper - The Periodic Table of the Elements - Formation Inc. - The Information Corporation
These are the so called Cuprate Superconductors, discovered in 1986.
At that point in time (March 1997), it was quite easy for anyone to see, that there was something that wasn't quite right, in Theoretical and Condensed Matter Physics.
A Bismuth containing Cuprate, BiSrCaCuO (BSCCO) has become the most stable and non-toxic working compound within High Temperature Superconductivity Science and Technology.
www.lifeform.org /elements/copper.htm   (390 words)

 Unconventional superconductor - Wikipedia, the free encyclopedia
It was a Lanthanum-based cuprate perovskite material with critical temperature of approximately 35 K (-238 degrees Celsius).
Nevertheless at present it is considered unlikely that cuprate perovskite materials will achieve room-temperature superconductivity.
but that are not cuprate perovskites have been discovered.
en.wikipedia.org /wiki/Unconventional_superconductor   (466 words)

 The oxygen isotope effect on the in-plane penetration depth in cuprate superconductors
It is observed that different cuprate families show similar doping dependences of the OIE on T
was observed in various cuprate families at all doping levels, suggesting that cuprate HTS are non-adiabatic superconductors.
The observation of these unusual isotope effects implies that lattice effects play an essential role in cuprate HTS and have to be considered in any realistic model of high-temperature superconductivity.
stacks.iop.org /0953-8984/16/S4439   (408 words)

 POSTER SESSION 1PO3: Cuprate-Based Materials
Superconducting properties of the oxychloride cuprates of Sr-Ca-Cu-O-Cl EPR Spectra of Gd3+ Ions and Localized Copper Centers in Gd0.5La0.5Ba2Cu3O6+x Compound
Nonhomogeneous pressure dependence of the superconducting transition temperature in multilayer cuprates
Cuprate Spin Ladder compounds doping measurements by X-ray absorption at the L3 copper edge
m2s-conf.uh.edu /abstracts/1PO3.html   (1194 words)

 Table of Contents for Anderson, P.W.: The Theory of Superconductivity in the High-Tc Cuprate Superconductors.   (Site not responding. Last check: 2007-10-08)
F.A.Q. The Theory of Superconductivity in the High-Tc Cuprate Superconductors
L. Conductivity between Luttinger Liquids in the Confinement Regime and c-Axis Conductivity in the Cuprate Superconductors David G. Clarke, S. Strong, and P. Anderson, PRL 74(22) (1995): 4499 345
R. The "Spin Gap" in Cuprate Superconductors P W Anderson, Journ.
press.princeton.edu /TOCs/c6085.html   (496 words)

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