Top PDF Orbital Approach to High Temperature Superconductivity

Orbital Approach to High Temperature Superconductivity

Orbital Approach to High Temperature Superconductivity

High temperature superconductivity (HTS) was discovered in 1986 by Bednorz and Műller [1]. Since then thousands of papers and more than four monographs have been written on this subject in attempts to explain the origin and nature of the phenomenon. Within the approximately thirty year period since then no mathematical theories have explained, or related, HTS to specific atoms in the Periodic Table. The ori- gin of HTS, or why it occurs specifically in cuprates, has not been given.

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Plaquette Valence Bond Theory of Cuprate High Temperature Superconductivity

Plaquette Valence Bond Theory of Cuprate High Temperature Superconductivity

spin state formation and the non-Fermi liquid charac- ter of the normal phase [6]. Unfortunately, details of his original approach, such as suppression of interlayer hopping in the normal phase as the main factor of super- conductivity, seems to contradict experimental data [11]. The latest version of the RVB theory is presented in [12]. We believe, that the main assumption of the strongly correlated limit as the base of understanding the high- temperature superconductivity is correct, as well as em- phasizing a crucial role of spin singlet states, but impor- tant details were missing. Below we present arguments for the thesis, that the minimal object of HTSC-theory is the plaquette in the so-called effective t, t 0 Hubbard model [13], rather than the conventional atomic limit typical for the theory of Mott insulators [6, 9]. The best practical realization of this atomic based theory is the dynamical mean-field theory (DMFT) [14]. The obvi- ous minimal generalization in the case of d x 2 −y 2 -wave
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Theory on another type of temperature-independent superconductivity based on circuit approaches with high critical current density

Theory on another type of temperature-independent superconductivity based on circuit approaches with high critical current density

This paper proposes a method to generate a new type of superconductivity that is temperature independent with a high critical current density. This study is significant because the method does not require refrigeration, specific setups, or specific substances. That is, the method for generating the superconductivity is very simple. Many conventional superconductor studies have not yet reached this point. Moreover, compared with our previously developed superconductivity (PNS) [1-3], the critical currents in this study are much larger, which is important for practical applications. In the theoretical approaches, even though the mechanism of pairing, and the Bose–Einstein condensation are the same in this study as in PNS, the present paper emphasizes the mechanism of the Meissner effect in addition to formulating the critical current density. Further, we establish a simulation method with an equivalent circuit that reveals the superconductivity properties in terms of the transport current and the electromagnetic characteristics. The principles of the presented system are as follows:
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Macroscopic Quantum System, Highly Correlated Electron State, and High Temperature Superconductivity in Iron Pnictides

Macroscopic Quantum System, Highly Correlated Electron State, and High Temperature Superconductivity in Iron Pnictides

It is quite possible that, together with the ion state overlapping in the space between the Fe 2+ planes, a coales- cence of two 2D Wigner crystals of bosons (from both halves of the FeAs layer) and formation of a united crys- tal of bosons occur (Figure 6(c)). This is accompanied by increasing Coulomb interaction between the 1D boson Wigner crystals in the united 2D crystal (Figure 9). In addition, in the space between the Fe 2+ planes the united 2D Wigner crystal of bosons proves to be in a middle position (relative to the charged planes in the sandwich structure) (Figure 6(c)) in which its Coulomb interactions with all positively and negatively charged planes sur- rounding it compensate each other. This means there is nothing to inhibit delocalization of the united 2D Wigner boson crystal as a whole (along all π orbitals, i.e., without any resistance) and, hence, the delocalization can pro- vide superconductivity in the FeAs layer.
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Modelling high temperature superconductivity: A philosophical inquiry in theory, experiment and dissent

Modelling high temperature superconductivity: A philosophical inquiry in theory, experiment and dissent

11 The original appeal of phonons was their potential to explain the isotope effect in superconductors. Before Maxwell and Serin discovered the isotope effect experimentally, Herbert Frohlich (1950) had also set out a model of phonons predicting it. But neither Frohlich nor Bardeen could calculate the relevant quantities that they were interested in (the superconducting wave function, the energy of the superconducting state, and the effective mass of the electrons) even if their phonon model was successful in accounting for the isotope effect. With hindsight, we can see now that both approaches focused unwisely on individual electron energies rather than collective energy - the energy that arises from the interaction of many electrons. Asking the question originally posed by Landau, they were looking to explain superconductivity by finding an interaction that made the total energy of the superconducting state lower than that of the normal state. Wanting to maintain the role of phonons, since it had proved successful in accounting for the isotope effect, their problem then became that the energy from the electron-phonon interaction had to dominate that arising from the ordinary Coulomb repulsion of electrons. As Hoddeson (2001) recalls in an insightful biography of Bardeen, Bardeen confessed his frustration to Rudolf Peierls, complaining that all the methods he had tried could not crack this problem. However, with his keen interest in emerging experimental results, he had singled out the observation that "the wave functions for the
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A Simplified Approach to the Problems of Room Temperature Superconductivity

A Simplified Approach to the Problems of Room Temperature Superconductivity

An attempt to simplify the approach to the problems of room-temperature superconductors was done. The key factor has been highlighted—a giant spin-orbit interaction as a result of specific geo- metry of crystal. Considering oriented carbyne as an example, it was shown that maximal value of SOC was attained in low-dimensional systems. A qualitative model of superconductivity in the lo- calized phase with “pseudo-magnetic field” and “Rashba effective field” as parameters was pre- sented. Their correlation was shown via geometry of electric microfields of crystal. Oriented car- byne was presented as localized phase of room-temperature superconductor and the recipe of its transformation to macroscopic superconductivity was given.
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A Different Approach to High Tc Superconductivity: Indication of Filamentary Chaotic Conductance and Possible Routes to Room Temperature Superconductivity

A Different Approach to High Tc Superconductivity: Indication of Filamentary Chaotic Conductance and Possible Routes to Room Temperature Superconductivity

The composition for such composites will be passed 4 by the empirical relation of Tco = 2740 q c that connects the transition temperature Tco of optimum doped superconductors with the me[r]

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Superconductivity and Superfluidity Part I: The development of the science of superconductivity and superfluidity in the 20th century

Superconductivity and Superfluidity Part I: The development of the science of superconductivity and superfluidity in the 20th century

At the beginning of the twentieth century, a new form of scientific research of appeared in the world. Heike Kamerling-Onnes was one of first scientists who used the industry for the service of physics. His research laboratory was based on the present plant of freeze consisting of refrigerators which he developed. This industrial approach gave him complete benefits of the world monopoly in studies at low temperatures for a long time (15 years!). Above all, he was able to carry out his solid-state studies at liquid helium (which boils at atmospheric pressure at 4.18 K). He was the first who creates liquid helium in 1908,then he began his systematic studies of the electrical resistance of metals. It was known from earlier experiments that the electrical resistance of metals decreases with decreasing temperature. Moreover, their residual resistance turned out to be smaller if the metal was cleaner. So the idea arose to measure this dependence in pure platinum and gold. But at that time, it was impossible to get these metals sufficiently clean. In those days, only mercury could be obtained at a very high degree of purification by method of repeated distillation. The researchers were lucky. The superconducting transition in mercury occurs at 4.15K, i.e. slightly below the boiling point of helium. This has created sufficient conditions for the discovery of superconductivity in the first experiment.
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High orbital angular momentum harmonic generation

High orbital angular momentum harmonic generation

every pump mode and the seed. The beating of these two plasma modes with the pump is at the onset of the cascading mechanism that leads to the high OAM harmonic generation. The pump l 00 beating with the plasma l 01 − l 1 preserves the initial OAM if a new seed component appears with l 1 þ Δl ( Δl ≡ l 00 − l 01 ). Similarly, the pump l 01 beating with the plasma l 00 − l 1 preserves the OAM if another seed mode component grows with l 1 − Δl . These are the first OAM sideband harmonics growing in the seed. Each of these sidebands will beat with the pump, adding new higher-order OAM sidebands to the plasma wave. In general, each new mode in the plasma wave continues to interact with every pump mode, generating higher OAM seed modes l 1 mΔl , with integer m . The high OAM harmonics then appear because the plasma wave is in a superposition of OAM states. This unexpected behavior, due to the wavelike plasma response, has no counterpart in other optical devices such as spiral wave plates.
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Martin, Marianne
  

(2011):


	High-Temperature Superconductivity in Doped BaFe2As2.


Dissertation, LMU München: Fakultät für Chemie und Pharmazie

Martin, Marianne (2011): High-Temperature Superconductivity in Doped BaFe2As2. Dissertation, LMU München: Fakultät für Chemie und Pharmazie

meantime, it is accepted that the formation of Cooper pairs in MgB 2 is also phonon-mediated and can be well explained by an expanded BCS theory. [8] Finally, in March 2008, the discovery of high-T C superconductivity in the iron arsenide oxides [9] has heralded a new era in superconductivity research. After the first report on LaFeAs(O 1-x F x ) with a critical temperature T C of 26 K, even higher transition temperatures up to 55 K in fluoride doped SmFeAs(O 1-x F x ) followed quickly. [10] These materials, which are based on two-dimensional iron arsenide layers separated by rare earth oxide layers, represent the second class of high-T C superconductors after the discovery of the cuprates more than 20 years ago. [2] This is especially surprising, since historically the antagonistic relationship between superconductivity and magnetism has led researchers to avoid the use of magnetic elements, while these new superconductors contain high concentrations of the ferromagnetic metal iron. Therefore, few would have anticipated that an iron-containing material could show such an extraordinary T C . In the meantime, the maximum T C for the iron arsenides in general is 56.3 K (Gd 1-x Th x FeAsO with
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One year study of Transverse and Vertical Diameter of the Orbit as a parameter in sex determination of human skull: June 2005 - May 2006

One year study of Transverse and Vertical Diameter of the Orbit as a parameter in sex determination of human skull: June 2005 - May 2006

As Krogman puts that in sexing a skull, the initial impression often is the deciding factor, in my opinion the diameters of transverse and vertical of orbital margins or openings gives an initial impression of sexing a given skull. To say so, the present observations show that committing an error in determining the sex of a given skull will be less than one in hundred which givens much creditability to the present work. It is also highly significant to note that the orbital index show a clear marginal variation for each sex.

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Classifying superconductivity in ThH-ThD superhydrides

Classifying superconductivity in ThH-ThD superhydrides

3 Recent interest to the isotope effect in superconducting compounds based on isotopes of hydrogen is based on experimental discovery of near-room-temperature superconductivity in H 3 S-D 3 S [12] and LaH 10 [13]. It should be stressed that to date there is no clarity on the

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Origin of high orbital eccentricity and inclination of asteroids

Origin of high orbital eccentricity and inclination of asteroids

at individual semi-major axes, are shown in the Fig. 1. In- clination (i) is given in radian in this paper. Relative ve- locities between asteroids are similar to the random veloc- ities. The root mean square of random velocities is about 4.8 km/s. Above the dotted-broken line, orbits of asteroids with i = 0 cross the Martian orbit (1.52 AU) and above the dashed line they cross the Jovian orbit (5.20 AU). Aster- oids above these lines closely approach the planets and can be strongly scattered. Arrows show the locations of strong resonances. The inclinations of asteroids are excited at the location of the secular resonance called ν 16 , and their eccen-
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Amygdalar reactivity is associated with prefrontal cortical thickness in a large population based sample of adolescents

Amygdalar reactivity is associated with prefrontal cortical thickness in a large population based sample of adolescents

Several limitations of the present study should be noted. In rodent models of chronic stress, structural changes and increased neuronal excitability have been reported in the amygdalae [58–60]. Furthermore, there is evidence that such functional and structural changes in the amygdalae undergird the emergence of anxiety-like symptoms in rodent models of chronic stress [58–60]. That being said, we can only speculate as to the developmental origins of the observed structure-function relationship in the present study. As members of our group have previously discussed [35], it is possible that reduced thickness in prefrontal regulatory regions —reflecting compromised cytoarchitectonic integrity—results in a diminished capacity to downregulate amygdalar activity. It is also possible that increased amygdalar reactivity, over time, results in structural damage to prefrontal cortices through continued activation of the hypothalamic-pituitary-adrenal (HPA) axis and resultant release of cortisol [61–64]. Both of these processes could potentially account for the structure-function association in the present study; future studies, however, are needed to directly test these potential explanations. We can- not rule out the possibility that structure-function relations observed in the present study reflect parallel, experience-driven developmental processes that are independent of underlying anatomical connectivity. With regard to our group analyses, it should be noted that the “high reactive” group possessed significantly lower Performance IQs relative to all other participants. We cannot rule out the possibility that this difference in Performance IQ may have contrib- uted to the observed cortical thickness differences. To address this issue, we examined the rela- tionship between Performance IQ and cortical thickness while controlling for age, total brain volume, sex, site, handedness, SES, Verbal IQ, and pubertal development. Critically, no signifi- cant associations were
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Rhodium Sets New Standards170-174

Rhodium Sets New Standards170-174

When searching for the possible superconductivity of rhodium the Jiilich low temperature team discovered in a sample with a residual resistivity ratio (RRR) of 50 a weak diam[r]

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Use of a Knowledge Base of Subject Relationship for Enhancing Retrieval Performance in the Digital Environment

Use of a Knowledge Base of Subject Relationship for Enhancing Retrieval Performance in the Digital Environment

In order to acquire the knowledge of subject interrelationship, usually experts are consulted. Also, co-citation, co-word, co-classification maps can be used in this context. It is specifically pointed out by Todorov(1989) that Co-citation maps generated at macro level are difficult to validate using traditional quantitative approaches. Same is the case with co-word maps. Hence, co-classification analysis of a subject based on a classification scheme is considered more effective. The source of data for such co- classification is Physics Abstract. The subject chosen is superconductivity. Subject relationship data is collected for the period 1985-93 from the printed abstract. From this, a “toy” knowledge based system for superconductivity subject relationship is developed and is used to demonstrate how Knowledge based system of subject relationship can be used in enhancing retrieval efficiency.
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Relativistic BCS-BEC Crossover at Quark Level

Relativistic BCS-BEC Crossover at Quark Level

relativistic fermion systems. The theory recovers the BCS mean field approximation at zero temperature and the non-relativistic results in a proper limit. For massive fermions, when the coupling strength increases, there exist two crossovers from the weak coupling BCS superfluid to the non-relativistic BEC state and then to the relativistic BEC state. For color superconductivity at moderate baryon density, the matter is in the BCS-BEC crossover region, and the behavior of the pseudogap is quite similar to that found in high temperature superconductors.

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High Pressure Band Structure, Metallization and Superconductivity of ZnSe and CdSe

High Pressure Band Structure, Metallization and Superconductivity of ZnSe and CdSe

metallization, which leads to the superconductivity in ZnSe and CdSe. The superconducting transition temperatures (Tc) of ZnSe and CdSe are obtained as a function of pressure for NaCl structure. ZnSe and CdSe come under the class of pressure induced superconductors. When pressure is increased Tc increases in both compounds. The dependence of Tc on electron - phonon mass enhancement factor λ shows that ZnSe and CdSe are electron-phonon-mediated superconductors.

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Classifying superconductivity in an infinite-layer nickelate Nd 0.8 Sr 0.2 NiO 2

Classifying superconductivity in an infinite-layer nickelate Nd 0.8 Sr 0.2 NiO 2

[27] Talantsev E F, Mataira R C, Crump W P 2019 Classifying superconductivity in Classifying superconductivity in Moiré graphene superlattices arXiv:1902.07410v3 [28] Fête A, Rossi L, Augieri A and Senatore C 2016 Ionic liquid gating of ultra-thin YBa 2 Cu 3 O 7-x films Applied Physics Letters 109 192601

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Superconductivity in ropes of carbon nanotubes

Superconductivity in ropes of carbon nanotubes

The hope to use molecules as the ultimate elementary building blocks for electronic circuits has motivated the quest to understand electronic transport in thinner and thinner wires, ideally with one or two conduction modes. However, a number of physical phenomena tend to drive one-dimensional (1D) metallic wires to an insulating state at low temperature. Carbon nanotubes, because of their special band structure, can escape such a fate and remain conducting over lengths greater than one micron down to very low temperature [1, 2]. Moreover, transport through nanotubes has been shown to be quantum coherent [3]. This is also demonstrated by the existence of strong supercurrents when individual nanotubes are connected to superconducting contacts [4, 5]. The observation of intrinsic superconductivity in ropes of carbon nanotubes containing a few tens of tubes [6, 7] is even more surprising and indicates the presence of attractive pairing interactions which overcome the strong repulsive interactions. This phenomenon is described in the present paper, both from the experimental and the theoretical point of view. A single-wall nanotube (SWNT) is made of a single graphene plane wrapped into a cylinder. The Fermi surface of graphene reduces to two discrete points (usually denoted as K and K ′ ) at the corners of the first
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