scholarly journals Extremely Overdoped Superconducting Cuprates via High Pressure Oxygenation Methods

2021 ◽  
Vol 6 (4) ◽  
pp. 50
Author(s):  
Linda Sederholm ◽  
Steven D. Conradson ◽  
Theodore H. Geballe ◽  
Chang-Qing Jin ◽  
Andrea Gauzzi ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature Superconductivity ◽  
Chemical Activity ◽  
Excess Oxygen ◽  
Excess Charge ◽  
P Values ◽  
Superconducting Cuprates ◽  
Upper Limit ◽  
Extensive Search ◽  
Normal Fermi

Within the cuprate constellation, one fixed star has been the superconducting dome in the quantum phase diagram of transition temperature vs. the excess charge on the Cu in the CuO2-planes, p, resulting from O-doping or cation substitution. However, a more extensive search of the literature shows that the loss of the superconductivity in favor of a normal Fermi liquid on the overdoped side should not be assumed. Many experimental results from cuprates prepared by high-pressure oxygenation show Tc converging to a fixed value or continuing to slowly increase past the upper limit of the dome of p = 0.26–0.27, up to the maximum amounts of excess oxygen corresponding to p values of 0.3 to > 0.6. These reports have been met with disinterest or disregard. Our review shows that dome-breaking trends for Tc are, in fact, the result of careful, accurate experimental work on a large number of compounds. This behavior most likely mandates a revision of the theoretical basis for high-temperature superconductivity. That excess O atoms located in specific, metastable sites in the crystal, attainable only with extreme O chemical activity under HPO conditions, cause such a radical extension of the superconductivity points to a much more substantial role for the lattice in terms of internal chemistry and bonding.

scholarly journals High temperature superconductivity in sulfur hydride under ultrahigh pressure: A complex superconducting phase beyond conventional BCS

2016 ◽  
Vol 2 (1) ◽  
Author(s):  
Annette Bussmann-Holder ◽  
Jürgen Köhler ◽  
M.-H. Whangbo ◽  
Antonio Bianconi ◽  
Arndt Simon
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Transition Temperature ◽  
Hydrogen Bonds ◽  
Pressure Dependence ◽  
High Temperature Superconductivity ◽  
Superconducting Phase ◽  
Ultrahigh Pressure ◽  
Phonon Modes ◽  
Interband Coupling

AbstractThe recent report of superconductivity under high pressure at the record transition temperature of Tc =203 K in pressurized H2S has been identified as conventional in view of the observation of an isotope effect upon deuteration. Here it is demonstrated that conventional theories of superconductivity in the sense of BCS or Eliashberg formalisms cannot account for the pressure dependence of the isotope coefficient. The only way out of the dilemma is a multi-band approach of superconductivity where already small interband coupling suffices to achieve the high values of Tc together with the anomalous pressure dependent isotope coefficient. In addition, it is shown that anharmonicity of the hydrogen bonds vanishes under pressure whereas anharmonic phonon modes related to sulfur are still active.

HIGH-TEMPERATURE SUPERCONDUCTIVITY CAUSED BY CIRCULAR POLARIZED ZERO-POINT OSCILLATION

2001 ◽  
Vol 15 (08) ◽  
pp. 219-224 ◽  
Author(s):  
MASANORI SUGAHARA ◽  
NICKOLAI N. BOGOLUBOV
Keyword(s):  
High Temperature ◽  
High Temperature Superconductivity ◽  
Particle System ◽  
Stable State ◽  
Zero Point ◽  
Particle State ◽  
Pure Crystal ◽  
Upper Limit ◽  
Conduction Plane ◽  
Laughlin States

A new model is proposed on the recently found non-cuprate high temperature superconductivity in crystal with 2D conduction plane which is composed of the planar connection of many circular localized orbits. Our findings are as follows: (i) the ground state of the doped 2D particle system in zero point oscillation is similar to the particle state in very strong magnetic field, (ii) Laughlin state with filling factor ν = 1/2 is the most stable state of the 2D particle system, (iii) the superposition of many fluctuating Laughlin states in pure crystal gives a coherent state with superfluidity. (iv) This model gives an estimation of the upper limit of the superconductivity transition temperature: [Formula: see text] for fcc C 60, and [Formula: see text] for Ag β Pb 6 CO 9, which are close to observation.

scholarly journals A field-wide assessment of differential high throughput sequencing reveals widespread bias

2021 ◽  
Author(s):  
Taavi Päll ◽  
Hannes Luidalepp ◽  
Tanel Tenson ◽  
Ülo Maiväli
Keyword(s):  
High Throughput ◽  
Marked Improvement ◽  
High Throughput Sequencing ◽  
Experimental Treatment ◽  
Data Repository ◽  
P Value ◽  
P Values ◽  
Upper Limit ◽  
File Structures ◽  
Over Time

AbstractHere we assess reproducibility and inferential quality in the field of differential HT-seq, based on analysis of datasets submitted 2008-2019 to the NCBI GEO data repository. Analysis of GEO submission file structures places an overall 59% upper limit to reproducibility. We further show that only 23% of experiments resulted in theoretically expected p value histogram shapes, although both reproducibility and p value distributions show marked improvement over time. Uniform p value histogram shapes, indicative of <100 true effects, were extremely few. Our calculations of π0, the fraction of true nulls, showed that 36% of experiments have π0 <0.5, meaning that in over a third of experiments most RNA-s were estimated to change their expression level upon experimental treatment. Both the fraction of different p value histogram types and π0 values are strongly associated with the software used for calculating these p values by the original authors, indicating widespread bias.

13.—A Search for the Quark in Extensive Air Showers, using a Counter-controlled Cloud Chamber

1972 ◽  
Vol 70 ◽  
pp. 143-153 ◽  
Author(s):  
G. R. Evans ◽  
N. E. Fancey ◽  
J. Muir ◽  
A. A. Watson
Keyword(s):  
High Pressure ◽  
Cloud Chamber ◽  
Extensive Air Showers ◽  
Acceptance Angle ◽  
Air Showers ◽  
Experimental Conditions ◽  
Counting Technique ◽  
Upper Limit ◽  
Statistical Variations ◽  
Singly Charged

SynopsisA search is reported for the relativistic e/3 quark among the cores of Extensive Air Showers initiated by primaries with energies greater than 1014 eV. The detector is a high-pressure cloud chamber filled with helium at 28 atmospheres, and is counter controlled. The experimental conditions avoid the criticisms levelled at the McCusker experiment and are such that the tracks of e/3 quarks cannot be simulated by singly charged shower particles either through statistical variations in primary ionisation or otherwise. The primary ionisation density, measured using a gap-counting technique on post-expansion electron and muon tracks, is compared with predictions from the theory of Budini et al. (1960). The agreement achieved shows that the theory is a reliable foundation for methods of identifying quark candidates, and measuring charges. The experiment has been running for 5000 hours. No quark candidates have been found. With an acceptance angle of 0·3 sr and an area of 140 cm2, this sets the upper limit of flux of e/3 quarks at 4 × 10−9 cm−2 sec−1 sr−1 with 95 per cent, confidence. The experiment is being continued.

Prediction of superconducting ternary hydride MgGeH6: from divergent high-pressure formation routes

2017 ◽  
Vol 19 (40) ◽  
pp. 27406-27412 ◽  
Author(s):  
Yanbin Ma ◽  
Defang Duan ◽  
Ziji Shao ◽  
Da Li ◽  
Liyuan Wang ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Ab Initio ◽  
Phase Diagrams ◽  
High Temperature Superconductivity ◽  
High Pressure Phase ◽  
Pressure Phase

Invigorated by the high temperature superconductivity in some binary hydrogen-dominated compounds, we systematically explored high-pressure phase diagrams and superconductivity of a ternary Mg–Ge–H system usingab initiomethods.

Electronic Properties of Magnetic Superconductor HoNi2B2C Under High Pressure

2003 ◽  
Vol 17 (18n20) ◽  
pp. 3664-3671 ◽  
Author(s):  
G. Oomi ◽  
N. Matsuda ◽  
T. Kagayama ◽  
C. K. Cho ◽  
P. C. Canfield
Keyword(s):  
Magnetic Field ◽  
High Pressure ◽  
Electrical Resistivity ◽  
Fermi Liquid ◽  
High Pressures ◽  
Metamagnetic Transition ◽  
Liquid Behavior ◽  
The Stability ◽  
Normal Fermi ◽  
Fermi Liquid Behavior

The electrical resistivity of single crystalline HoNi 2 B 2 C has been measured at high pressure and magnetic fields. The three anomalies in the magnetoresistance due to metamagnetic transitions are observed both at ambient and high pressures. It is found that the metamagnetic transition fields increase with increasing pressure. The temperature dependence of electrical resistivity is strongly dependent on magnetic field. Non Fermi liquid behavior is observed near the metamagnetic transition fields. But the normal Fermi liquid behavior recovers after completing the phase transition. The Grüneisen parameters are also calculated to examine the stability of electronic state.

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