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An Evaluation of Temperature Dependent Hall Coefficient
of High TC - Superconductor

An Evaluation of Temperature Dependent Hall Coefficient of High TC - Superconductor

In this paper, using the theoretical model developed for low energy spin and charge excitation of metal oxides and doped fullerenes, we have studied the temperature dependent Hall coefficient for high Tc superconductor YBa2Cu3O7- δ (Tc = 92K). We have used different value of δ which gives the oxygen difficiency. In section 2.0, we have presented the mathematical formula used in the evaluation. In section 3.0, we have given the discussion of result. Tables and references are given in the last section of the paper.
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AN EVALUATION OF PSEUDO GAP IN HIGH TC- SUPERCONDUCTORS IN BCS-BEC CROSSOVER REGION

AN EVALUATION OF PSEUDO GAP IN HIGH TC- SUPERCONDUCTORS IN BCS-BEC CROSSOVER REGION

Abstract: We have studied the Pseudo gap in high Tc-superconductors through pairing scenario based on Nozieres and Schmitt - Rink theory. The central theme of this theory is the Cross-over problem from BCS superconductivity to Bose-Einstein Condensation (BEC). Pseudo gap state is regarded as a cross-over region. There is a co-existence of fermions and bosons in this region. Evaluating the self-energy from T-matrix approach, we have observed the Pseudo gap in the single particle excitation. The spectral function clearly shows the Pseudo gap in the single particle spectrum which appears in the cross-over region.
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The Correlation of Miller Indices with the Conductivity Mechanism of Cu Based  High Tc Superconductor

The Correlation of Miller Indices with the Conductivity Mechanism of Cu Based High Tc Superconductor

The obtained results showed the peaks related to high superconductor phase Cu-1223, which were more than the low phase of Cu-1212. The ratio of high phase was about 74% of the whole structure. This result agreed with the data sheet concluded from database information for low phase Cu-1212 and high phase Cu-1223. The appearance of two phases accepted due to a polycrystalline structure. The XRD analysis was applied in the Refine program in order to find the lattice parameter a = b = 4.171 Å and c = 16.743 Å. It found that Cu-1223 had a tetragonal phase, and the lattice constants were larger than the lattice pa- rameter for Hg-1223 especially in the basal plane [8]. That was might be attri- buted to high oxidation of Cu-ion rather than Hg-ion in the basal plane, which made more absorption of extra oxygenin comparison with Hg-1223. The data- base of (ICDD) with pdf file (98-004-1652) was used to analysis the pattern of Cu-1223 system. The small change in lattice constant might be related to the variation of (2θ) position. The observed change in lattice parameters was agreed with the strain happened in Cu-1223 compound that was about (0.885 ± 0.149).
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What can be learned about high-tc from local density theory

What can be learned about high-tc from local density theory

In H0 the electronic structure of the isolated d-shell, including crystal field splittings and the quasi-atomic Coulomb interactions, as well as the bands arising from th[r]

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Possible twin boundary effect upon the properties of high Tc superconductors

Possible twin boundary effect upon the properties of high Tc superconductors

We have studied the field at which superconductivity nucleates in grain-aligned samples of Y1Ba2Cu3O7-δ very close to the transition temperature Tc. For the field parallel to the c axis and for temperatures within 2 K of Tc, the nucleation field is found to vary as (1-T/Tc)1/2. The data suggest that superconductivity localized near twin boundaries may exist at temperatures close to Tc. .AE

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Critical Current of Low Angle Grain Boundaries in High Tc Superconductors

Critical Current of Low Angle Grain Boundaries in High Tc Superconductors

High-temperature superconducting (HTS) materials produced on the base of ‘cuprate’ compounds (RE)-Ba-Cu-O (RE – is the rare-earth element: Y, Gd, Nd) are of great practical interest for electrical engineering and electronics [1]. First of all it concerns the possibility of large-scale applications, such as: superconducting electric power cables, high-field magnets, motors, energy storage devices, ets. This interest is caused by a large current carrying ability of HTS materials, allowing dissipation-free current flow with densities more than 10 6 A/cm 2 at liquid nitrogen temperature
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On the Isotope Like Effect for High Tc Superconductors in the Scenario of 2 Phonon Exchange Mechanism for Pairing

On the Isotope Like Effect for High Tc Superconductors in the Scenario of 2 Phonon Exchange Mechanism for Pairing

Abstract By generalizing the isotope effect for elemental superconductors SCs to the case of pairing in the 2-phonon exchange mechanism for composite SCs, we give here an explanation of [r]

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EFFECTIVE-MEDIUM THEORY FOR GRANULAR HIGH-TC SUPERCONDUCTORS ELECTROMAGNETIC PROPERTIES IN THE MICROWAVE REGION

EFFECTIVE-MEDIUM THEORY FOR GRANULAR HIGH-TC SUPERCONDUCTORS ELECTROMAGNETIC PROPERTIES IN THE MICROWAVE REGION

At the higher infra-red frequencies, the normal dielectric properties take over and superconductivity loses its significance, apart from the characteristic frequencies associ[r]

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Microstructural and High Tc Dielectric Properties of Microwave Sintered Ba0.7Ca0.3TiO3 (BCT) Ceramic

Microstructural and High Tc Dielectric Properties of Microwave Sintered Ba0.7Ca0.3TiO3 (BCT) Ceramic

variation of loss tangent with temperature for BCT ceramic sintered at 1100°C and 1200°C respectively. Here, increment in magnitude (almost double) of dielectric constant was observed for ceramic sintered at 1200°C while the dielectric loss tangent value is low as compared with ceramic sintered at lower temperature (1100°C). This increment in dielectric constant may attributes because of improved microstructure resulted due to more diffusion of Ca 2+ ions on Ba 2+ site with increasing temperature this may be resulted due to diffusion of Ca ions fill the voids results high dense microstructure. Density of the material is an very important factor in case of
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Synthesis, Structural and Magnetic Study of Pure and Pr Doped Eu-123 High Tc Superconductors

Synthesis, Structural and Magnetic Study of Pure and Pr Doped Eu-123 High Tc Superconductors

The lattice parameters, oxygen content, volume of unit cell, average charge on Cu–O plane were evaluated from X-ray diffraction data.. From XRD data, it is observed that t[r]

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Magnetic and structural transitions in the iron chalcogenide high Tc superconductor: K0 8Fe1 76Se2 00

Magnetic and structural transitions in the iron chalcogenide high Tc superconductor: K0 8Fe1 76Se2 00

and sine modes in conventional spectrometers. Calibration was done using an a-Fe foil as a reference. Two closed-cycle He refrigerators were used in addition to a furnace for the high temperature data. One sample was cycled through the Ne´el temperature twice and another was cycled three times, spending over a week above 550 K. Contrary to reports by Nowik et al., 7 we observed no degradation of the samples below 673 K and the I4/m ! I4/mmm structural transition appeared to be reversible.

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Enhanced nematic fluctuations near an antiferromagnetic Mott insulator and possible application to high-Tc cuprates

Enhanced nematic fluctuations near an antiferromagnetic Mott insulator and possible application to high-Tc cuprates

The key point revealed by our classical Monte-Carlo simulations and large-N calculations is that the biquadratic term favors local stripe-like magnetic fluctuations, which result in an e[r]

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Magnetic Flux Quanta in High Tc/Low Tc
Superconducting Rings with

Magnetic Flux Quanta in High Tc/Low Tc Superconducting Rings with

In the measurements in zero magnetic field, complete junction breakdown is not observed, because the measurements were stopped when the junctions started to break down. This start of the breakdown of the junctions is shown in figure 5.4. In the figure it can be seen that a current is flowing across the junctions towards the inner edge of the ring. This implies that the junctions have been broken down. This breakdown can be explained by the high currents flowing in the ring. Since in this experiment the magnetic field is set to zero, all magnetic flux through the ring has to be generated by the current circulating in the ring. To generate this flux the current has reached a value that is higher than the critical current for that junction. Because the sample containing the rings is already more than five years old, it is possible that the junctions have deteriorated, for example by oxidation of the niobium to insulating NbO x obtaining the required oxygen from the neighboring
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Broken rotational symmetry on the Fermi surface of a high Tc superconductor

Broken rotational symmetry on the Fermi surface of a high Tc superconductor

low θ near the ϕ = 90° directions; and suppression of AMR along the ϕ = 90° direction at high θ. The semi-classical conductivity of a metal is given by the velocity-velocity correlation function of all quasiparticles on the Fermi surface, averaged over their lifetime τ . 36, 37 Magnetoresistance arises because the quasiparticle velocity — which is always perpendicular to the Fermi surface — is altered by the Lorentz force, which induces cyclotron motion perpendi- cular to the magnetic field (see Fig. 2a for a schematic cyclotron orbit). If τ is sufficiently long, orbiting quasiparticles sample a signi fi cant portion of the Fermi surface perimeter before scatter- ing. Depending on the speci fi c geometry of the cyclotron orbit, components of the quasiparticle velocity (v z , for example) may
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Superconducting fluctuations and pseudogap in high-Tc cuprates

Superconducting fluctuations and pseudogap in high-Tc cuprates

A phase fluctuation contribution might be invoked for the most underdoped samples in a T range which increases when controlled disorder is introduced by electron irradiation.. Quantitati[r]

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An Evaluation of Pseudo Gap in High Tc-Superconductor

An Evaluation of Pseudo Gap in High Tc-Superconductor

The pseudo gap in the single particle spectrum can be derived from spin fluctuation theory but the crucial problem is on the magnetic excitation which has been observed i[r]

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Evidence for a generic quantum transition in high Tc cuprates

Evidence for a generic quantum transition in high Tc cuprates

Zero-field 共 ZF 兲 and transverse-field 共 TF 兲 ␮ SR studies were performed at the pulsed muon source, ISIS Facility, Rutherford Appleton Laboratory. Spectra were collected down to as low as 40 mK thus allowing the temperature dependence of slow spin fluctuations to be studied to high doping. In a ␮ SR experiment, 100% spin-polarized positive muons implanted into a specimen precess in their local mag- netic environment. Random spin fluctuations will depolarize the muons provided they do not fluctuate much faster than the muon precession. The muon decays with a life time 2.2 ␮ s, emitting a positron preferentially in the direction of the muon spin at the time of decay. By accumulating time histograms of such positrons one may deduce the muon de- polarization rate as a function of time after implantation. The muon is expected to reside at the most electronegative site of the lattice. In both HTS families studied here it is the O 2 ⫺ nearest to the planes 18 so the results reported here are domi- nated by the magnetic correlations in the CuO 2 planes. As we show below, this is confirmed by results in samples doped with Zn, which substitutes for Cu in the CuO 2 planes.
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An Evaluation of Isotope Coefficient Exponent α of
High Tc uperconductors

An Evaluation of Isotope Coefficient Exponent α of High Tc uperconductors

high temperature superconductors have a two dimensional structure. Various calculations 12-17 shows that there is a logarithmic singularity in density of states, one therefore expects that this singularity plays a dominant role in causing the anomalous behavior of the isotope effect. Theoretical Formulation

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PROPERTIES OF GRANULAR HIGH-TC SUPERCONDUCTORS IN AN EFFECTIVE MEDIUM THEORY

PROPERTIES OF GRANULAR HIGH-TC SUPERCONDUCTORS IN AN EFFECTIVE MEDIUM THEORY

We start by using an effective medium theory (EMT), for the conductivity and susceptibility, which is supplemented by London electrodynamics ,jbr the superconducting [r]

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The CXCR4 antagonist plerixafor (AMD3100) promotes proliferation of Ewing sarcoma cell lines in vitro and activates receptor tyrosine kinase signaling

The CXCR4 antagonist plerixafor (AMD3100) promotes proliferation of Ewing sarcoma cell lines in vitro and activates receptor tyrosine kinase signaling

We next investigated how these plerixafor effects related to CXCR4 receptor expressions of our cell line panel. Splicing isoforms and post-translational modifications such as glycosylation and ubiquitination can affect CXCR4 sur- face expression and function [27, 29]. Because such CXCR4 splicing variants have been reported in Ewing sarcoma [30, 31], we first examined CXCR4 protein expression in Western blots of whole cell lysates. This revealed multiple bands as previously shown in other cancers [27, 29] (Fig. 3a). A band of ~ 45 kDa corresponded to the glycosylated CXCR4 monomer and was present in all cell lines including HL-60, whereas a 55 kDa isoform was restricted to Ewing sarcoma lines and thus dispensable for the proliferative plerixafor-response of HL-60 cells. Using an alternative CXCR4 antibody, we detected add- itional bands, also attributable to previously described isoforms and suggestive of post-translational modifica- tions (Additional file 1). However, neither isoform cor- related with CXCR4 surface expression, as in addition to HL-60, four Ewing sarcoma cell lines (A673, TC-71, VH-64, DC-ES-6) showed minimal detectable surface expression (Fig. 3b and c). In contrast, TC-32 and CADO-ES1 cell lines revealed surface expression in more than 75% of their population (Fig. 3c), at levels (assessed by relative fluorescence intensity, RFI) that exceeded those of LAN-5, classified as high-level sur- face expressing among neuroblastoma cell lines [27] (Fig. 3d). Because CXCR4 expression of Ewing sarcoma cell lines had been found heterogeneous within cell populations and highly dynamic in response to serum deprivation and space constraints [20], we performed our analyses at a constant confluence of 70–80% and in both standard (10% serum) (Fig. 3) and serum-free growth con- ditions (Additional file 1). Cell lines with substantial CXCR4 surface expression (TC-32, CADO-ES1, LAN-5) recapitulated this heterogeneity in surface expression levels (Fig. 3b), and TC-32 and HL-60 cells demonstrated a RFI increase in serum-free medium, while the other cell lines did not show significant changes in surface- expressing fractions or RFI (Additional file 1). Thus, Ewing sarcoma cell lines consistently grouped into CXCR4-high (TC-32 and CADO-ES1) and CXCR4-low (A673, TC-71, VH-64, DC-ES-6) surface expression; in- dicating that substantial CXCR4 surface expression was not essential for proliferative and migratory responses to plerixafor that were observed in both groups.
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