Materials I: High-Tc Copper Oxides

2021 ◽  
pp. 228-280
Author(s):  
Vladimir Z. Kresin ◽  
Sergei G. Ovchinnikov ◽  
Stuart A. Wolf
Keyword(s):  
Order Parameter ◽  
High Temperature Superconductors ◽  
Upper Critical Field ◽  
Strong Impact ◽  
High Tc ◽  
Theoretical Concepts ◽  
Phonon Mechanism ◽  
Superconducting Compounds ◽  
History Of ◽  
Key Aspects

This chapter focuses on the cuprates, which are uniquely interesting superconducting compounds due to their high Tc, peculiar properties, and potential for applications. The history of the discovery of this very unusual class of superconductors is described, together with the properties and key theoretical concepts that can be used to understand their superconducting and normal behaviours. This chapter contains a description of some very key aspects of these materials: their very unusual phase diagram, where doping takes the compounds from antiferromagnetic insulators to high-temperature superconductors and finally to metallic conductivity; their very anomalous upper critical field Hc2; the symmetry of their order parameter; and the unusual isotope effect on Tc and penetration depth. There are two main approaches to the issue of the origin of high Tc in the cuprates: the phonon mechanism, with the strong impact of the polaronic effect, and a mechanism based on strong correlation effects.

What is the Symmetry of the High-Tc Order Parameter?

1998 ◽  
Vol 12 (29n31) ◽  
pp. 2920-2931 ◽  
Author(s):  
Richard A. Klemm
Keyword(s):  
High Temperature ◽  
Order Parameter ◽  
High Temperature Superconductors ◽  
Density Wave ◽  
Spin Density Wave ◽  
Superconducting Gap ◽  
S Wave ◽  
Orbital Symmetry ◽  
High Tc ◽  
Phase Sensitive

In recent years, there has been a raging controversy regarding the orbital symmetry of the superconducting order parameter (OP) in the high temperature superconductors. Many experiments were interpreted in terms of a dx2-y2-wave OP, but many others were interpreted in terms of a more conventional s-wave OP. We review the problems of both intrinsic and extrinsic natures with the phase-sensitive experiments on YBCO. We further show that the photoemission experiments of the purported superconducting gap in Bi2Sr2CaCu2O 8+δ are entirely consistent with charge- and/or spin-density wave formation in that material. The presence of such density waves greatly complicates the analysis of most experiments. Hence, we conclude that the orbital symmetry of the superconducting OP is still unknown in any of the high temperature superconductors.

scholarly journals The language of journalism - The language of agenda setting effects

2020 ◽  
pp. 11-18
Author(s):  
Maxwell McCombs
Keyword(s):  
Agenda Setting ◽  
Scientific Method ◽  
Large Scale ◽  
Theoretical Concepts ◽  
The Past ◽  
Intermedia Agenda Setting ◽  
History Of ◽  
Need For Orientation ◽  
Key Aspects

The evolution of agenda setting over the past 50 years is an in-depth, large-scale case study of the scientific method. This oscillating history of theoretical explication and extensive empirical investigation has identified major aspects of the language of journalism that have significant impact on the formation of public opinion. The theory of agenda setting now includes three levels of agenda setting effects, intermedia agenda setting and the concept of compelling arguments that identify key aspects of the language of journalism. Other theoretical concepts, need for orientation, and most recently civic osmosis and agendamelding explicate the process of agenda setting. All of these are intellectual tools for dealing with the contemporary problem of fake news.

scholarly journals THEORY OF HIGH-Tc SUPERCONDUCTING CUPRATES BASED ON EXPERIMENTAL EVIDENCE

1999 ◽  
Vol 13 (29n31) ◽  
pp. 3405-3418 ◽  
Author(s):  
A. A. ABRIKOSOV
Keyword(s):  
Order Parameter ◽  
Short Range ◽  
Inelastic Neutron Scattering ◽  
Positive Curvature ◽  
Spin Fluctuation ◽  
Upper Critical Field ◽  
Inelastic Neutron ◽  
High Tc ◽  
Superconducting Cuprates ◽  
Short Range Repulsion

A model of superconductivity in layered high-temperature superconducting cuprates is proposed, based on the extended saddle point singularities in the electron spectrum, weak screening of the Coulomb interaction and phonon-mediated interaction between electrons plus a small short-range repulsion of Hund's, or spin-fluctuation, origin. This permits to explain the large values of T c , features of the isotope effect on oxygen and copper, the existence of two types of the order parameter, the peak in the inelastic neutron scattering, the positive curvature of the upper critical field, as function of temperature etc.

Crystal chemistry of high-Tc superconductors

1990 ◽  
Vol 48 (4) ◽  
pp. 1118-1119
Author(s):  
Maryvonne Hervieu
Keyword(s):  
Oxygen Deficiency ◽  
Large Family ◽  
Copper Oxides ◽  
High Tc Superconductors ◽  
High Tc ◽  
Single Mechanism ◽  
Square Planar ◽  
History Of ◽  
Bismuth Cuprates ◽  
New Compounds

Four years after the discovery of superconductivity at high temperature in the Ba-La-Cu-O system, more than thirty new compounds have been synthesized, which can be classified in six series of copper oxides: La2CuO4 - type oxides, bismuth cuprates, YBa2Cu3O7 family, thallium cuprates, lead cuprates and Nd2CuO4 - type oxides. Despite their quite different specific natures, close relationships allow their structures to be simply described through a single mechanism. The fifth first families can indeed be described as intergrowths of multiple oxygen deficient perovskite slabs with multiple rock salt-type slabs, according to the representation [ACuO3-x]m [AO]n.The n and m values are integer in the parent structures, n varying from 0 to 3 and m from 1 to 4; every member of this large family can thus be symbolized by [m,n]. The oxygen deficient character of the perovskite slabs involves the existence or the co-existence of several types of copper environment: octahedral, pyramidal and square planar.Both mechanisms, oxygen deficiency and intergrowth, are well known to give rise easily to nonstoichiometry phenomena. Numerous and various phenomena have actually been characterized in these cuprates, strongly depending on the thermal history of the samples.

scholarly journals Ernst von Leyden (1832–1910): a pioneer in making oncology a respected medical discipline

2021 ◽  
Author(s):  
Peter Voswinckel ◽  
Nils Hansson
Keyword(s):  
International Association ◽  
German Society ◽  
Scientific Discipline ◽  
Strong Impact ◽  
Medical Discipline ◽  
History Of ◽  
National Socialists ◽  
New Research ◽  
German Physician

Abstract Purpose This article presents new research on the role of the renowned German physician Ernst von Leyden (1832–1910) in the emergence of oncology as a scientific discipline. Methods The article draws on archival sources from the archive of the German Society of Haematology and primary and secondary literature. Results Leyden initiated two important events in the early history of oncology: the first international cancer conference, which took place in Heidelberg, Germany, in 1906, and the founding of the first international association for cancer research (forerunner of today's UICC) in Berlin in 1908. Unfortunately, these facts are not mentioned in the most recent accounts. Both had a strong impact on the professionalization of oncology as a discipline in its own right. Conclusion Although not of Jewish origin, von Leyden was considered by the National Socialists to be “Jewish tainted”, which had a lasting effect on his perception at home and abroad.

scholarly journals The Gap and the Upper Critical FieldHc2as Function of Doping for High-TcCuprates

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
S. Orozco ◽  
R. M. Méndez-Moreno ◽  
M. A. Ortiz
Keyword(s):  
High Temperature ◽  
Critical Field ◽  
Energy Gap ◽  
High Temperature Superconductors ◽  
Upper Critical Field ◽  
Superconducting Gap ◽  
Phonon Interaction ◽  
As Doping ◽  
Electron Phonon Interaction ◽  
Wave Symmetry

The relation between thed-wave superconducting gapΔ0and the specific heat obtained with the Volovik effect is used to determine the upper critical fieldHc2as doping function, for high-temperature superconductors. A two-components model withd-wave symmetry, within the BCS framework, is introduced to describe the superconducting state. Generalized Fermi surface topologies are used in order to increase the density of states at the Fermi level, allowing the high-Tcvalues observed. The electron-phonon interaction is considered the most relevant mechanism for the high-Tccuprates, where the available phonon energy is provided by the half-breathing modes. The energy gap valuesΔ0calculated with this model are introduced to describe the variation of the upper critical fieldHc2as function of doping, forLa2-xSrxCuO4.

Anti-Sterilization Abuse Organizing: A Retrospective Examination

1988 ◽  
Vol 9 (2) ◽  
pp. 111-124
Author(s):  
Marian McDonald
Keyword(s):  
United States ◽  
Community Organizing ◽  
Reproductive Rights ◽  
The United States ◽  
Minority Women ◽  
Federally Funded ◽  
Theoretical Concepts ◽  
History Of ◽  
Retrospective Examination ◽  
The U.S

November 1988 marks the tenth anniversary of the U.S. Government's adoption of guidelines for federally-funded sterilizations. This action was the result of years of organizing by the anti-sterilization abuse movement which grew in the early 1970s in response to the alarming increase in numbers of coercive sterilizations, particularly among poor and minority women. This retrospective examination looks at the strengths and weaknesses of anti-sterilization abuse organizing in the United States, and draws out lessons for other areas of work. It begins by exploring the problem of sterilization abuse and the history of the movement against it. The movement is analyzed using key theoretical concepts of community organizing. An evaluation indicates that the anti-abuse efforts were successful and rich with lessons for reproductive rights and other popular health struggles today.

HISTORIOGRAPHY OF HISTORY OF THE STAVROPOL COSSACKS: KEY ASPECTS OF STUDYING THE REGIONAL COSSACK GROUP’S PAST

2021 ◽  
pp. 50-62
Author(s):  
K.A. Ushmaeva ◽  
◽  
A.S. Goncharov
Keyword(s):  
Comparative Method ◽  
Educational Institution ◽  
Practical Significance ◽  
Pedagogical Tools ◽  
Ideal Types ◽  
History Of ◽  
Historical Comparative ◽  
State Archives ◽  
Key Aspects ◽  
Economic Ties

This study is devoted to the study of relevant works on the history of the Stavropol Cossacks, works in the field of education of the Stavropol Cossacks as an independent Cossack group, trade, cultural and economic ties in the Stavropol Territory, spiritual life, language, culture, traditions and customs of the Stavropol Cossacks. Among modern studies in the history of the Stavropol Cossacks, the following topics stand out: military life and everyday life, folklore and song traditions, the movement for the revival of the Cossacks, as well as the current state and prospects for the development of Cossack organizations. The prospect of the development of pedagogical technologies based on the Cossack traditions of educating young people in Stavropol is highlighted as a separate topical topic. The relevance of the study lies in the need for a private study of the historiography of the regional Cossack group of Stavropol Cossacks in order to expand the scientific and pedagogical tools in the field of «Cossack studies». The practical significance of the study is expressed in the possibility of using the data of the article in the search for supporting material for teaching the "History of the Cossacks" in a higher educational institution (taking into account the regional specifics). The scientific novelty of the research is expressed in a new view of the Stavropol Cossacks as an independent Cossack group formed at the end of the XVIII century. The source base is represented mainly by archival data from the State Archives of the Stavropol Territory, data banks on archaeological, cultural and linguistic expeditions, sources of personal origin, the works of contemporary historians and directly the works of historians, whose studies formed the basis of the historiography of the history of the Stavropol Cossacks. The research methodology is based on the principles of historiographic comparative studies and comparative analysis of sources. Within the framework of the sociocultural approach, we rely on the following methods. Special-historical: the narrative method, the historical-comparative method, the historical-systemic method, the retrospective method. Sociological: document analysis, method of generalizing characteristics, method of ideal types. Culturological: comparative method, cultural-systemic method. Pedagogical: pedagogical interviewing, a method of studying and generalizing pedagogical experience.

Historiography of one city: colonialism, colonization, frontir. On the historiography of the history of functioning of the fortress city of the left wing of the Caucasian cordon line on the example of the history of Kizlyar in the first half of the 19th century

2020 ◽  
Vol 2020 (12-3) ◽  
pp. 250-258
Author(s):  
Mahomed Gasanov ◽  
Abidat Gazieva
Keyword(s):  
19Th Century ◽  
Historical Context ◽  
Left Wing ◽  
Theoretical Concepts ◽  
History Of ◽  
The 19Th Century ◽  
The City

The article is devoted to the analysis of the historiography of the history of the city of Kizlyar. This issue is considered in the historical context of the Eastern Caucasus. The author analyzes the three main theoretical concepts of the problem concerning Russia’s policy in the region, using the example of the city of Kizlyar in the context of historiography.

scholarly journals Potential high-Tc superconducting lanthanum and yttrium hydrides at high pressure

2017 ◽  
Vol 114 (27) ◽  
pp. 6990-6995 ◽  
Author(s):  
Hanyu Liu ◽  
Ivan I. Naumov ◽  
Roald Hoffmann ◽  
N. W. Ashcroft ◽  
Russell J. Hemley
Keyword(s):  
Group Structure ◽  
High Temperature Superconductors ◽  
Face Centered Cubic ◽  
Superconducting Transition ◽  
High Tc ◽  
Structure Search ◽  
Systematic Structure ◽  
Face Centered ◽  
Fcc Structure ◽  
Very High

A systematic structure search in the La–H and Y–H systems under pressure reveals some hydrogen-rich structures with intriguing electronic properties. For example, LaH10 is found to adopt a sodalite-like face-centered cubic (fcc) structure, stable above 200 GPa, and LaH8 a C2/m space group structure. Phonon calculations indicate both are dynamically stable; electron phonon calculations coupled to Bardeen–Cooper–Schrieffer (BCS) arguments indicate they might be high-Tc superconductors. In particular, the superconducting transition temperature Tc calculated for LaH10 is 274–286 K at 210 GPa. Similar calculations for the Y–H system predict stability of the sodalite-like fcc YH10 and a Tc above room temperature, reaching 305–326 K at 250 GPa. The study suggests that dense hydrides consisting of these and related hydrogen polyhedral networks may represent new classes of potential very high-temperature superconductors.

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