Charge transfer and carrier density in Bi-2212 high-Tc superconductors

1992 ◽  
Vol 104-107 ◽  
pp. 495-496
Author(s):  
H. Maletta ◽  
M. Weber ◽  
A. Amato ◽  
J. Bock ◽  
V.N. Duginov ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Carrier Density ◽  
High Tc Superconductors ◽  
High Tc

DESCRIPTION OF THE Tl, Pb and Bi CUPRATE HIGH-Tc SUPERCONDUCTORS AS INTERCALATION COMPOUNDS

1989 ◽  
Vol 03 (09) ◽  
pp. 723-728 ◽  
Author(s):  
R.S. MARKIEWICZ ◽  
B.C. GIESSEN
Keyword(s):  
Electron Transfer ◽  
Charge Transfer ◽  
Intercalation Compounds ◽  
Acceptor Site ◽  
High Tc Superconductors ◽  
High Tc ◽  
Stage Number ◽  
Graphite Intercalation ◽  
Superconducting Oxides

Treating the new superconducting oxides as intercalation compounds, especially, as analogues to graphite intercalation compounds (GIC), clarifies the understanding of a number of their properties; in this description, the ratio of the number of cuprate layers per intercalant unit is equivalent to the stage number in GIC’s. In particular, the role of charge transfer (presumably, electron transfer from oxygen in the [Formula: see text] sheets to an acceptor site located in the intercalant) in optimizing Tc can be well discussed in these terms, leading to the prediction that the curve of Tc versus n, the number of [Formula: see text] layers, must have a maximum at a specific value of n.

Local polarizability, structure, and charge-transfer in high-Tc superconductors

1995 ◽  
Vol 8 (4) ◽  
pp. 527-530 ◽  
Author(s):  
A. R. Bishop ◽  
J. T. Gammel ◽  
M. I. Salkola
Keyword(s):  
Charge Transfer ◽  
High Tc Superconductors ◽  
High Tc

scholarly journals Character of Doped Holes in Nd1−xSrxNiO2

2021 ◽  
Vol 6 (3) ◽  
pp. 33
Author(s):  
Tharathep Plienbumrung ◽  
Michael Thobias Schmid ◽  
Maria Daghofer ◽  
Andrzej M. Oleś
Keyword(s):  
Rare Earth ◽  
Charge Transfer ◽  
Charge Distribution ◽  
Hole Doping ◽  
Band Model ◽  
High Tc Superconductors ◽  
Transfer Energy ◽  
High Tc ◽  
Charge Transfer Energy ◽  
Two Band Model

We investigate charge distribution in the recently discovered high-Tc superconductors, layered nickelates. With increasing value of charge-transfer energy, we observe the expected crossover from the cuprate to the local triplet regime upon hole doping. We find that the d−p Coulomb interaction Udp makes Zhang-Rice singlets less favorable, while the amplitude of local triplets at Ni ions is enhanced. By investigating the effective two-band model with orbitals of x2−y2 and s symmetries we show that antiferromagnetic interactions dominate for electron doping. The screened interactions for the s band suggest the importance of rare-earth atoms in superconducting nickelates.

Cu d-d Orbital Transitions and Charge-Transfer Excitations in High-Tc Superconductors

1988 ◽  
pp. 195-200 ◽  
Author(s):  
H. P. Geserich ◽  
G. Scheiber ◽  
J. Geerk ◽  
H. C. Li ◽  
W. Weber ◽  
...  
Keyword(s):  
Charge Transfer ◽  
High Tc Superconductors ◽  
High Tc

Electronic carrier density in doped Bi-based high-Tc superconductors

1991 ◽  
Vol 185-189 ◽  
pp. 749-750
Author(s):  
M. Weber ◽  
A. Amato ◽  
J. Bock ◽  
V.N. Duginov ◽  
I.A. Gaganov ◽  
...  
Keyword(s):  
Carrier Density ◽  
High Tc Superconductors ◽  
High Tc

The many faces of STEM in materials science

1991 ◽  
Vol 49 ◽  
pp. 440-441
Author(s):  
John Silcox
Keyword(s):  
Materials Science ◽  
Auger Spectroscopy ◽  
Dark Field ◽  
High Tc Superconductors ◽  
High Tc ◽  
Acoustic Environment ◽  
Electromagnetic Vibration ◽  
The Many ◽  
Serial Mode

Determination of the microstructure and microchemistry of small features often provides the insight needed for the understanding of processes in real materials. In many cases, it is not adequate to use microscopy alone. Microdiffraction and microspectroscopic information such as EELS, X-ray microprobe analysis and Auger spectroscopy can all contribute vital parts of the picture. For a number of reasons, dedicated STEM offers considerable promise as a quantitative instrument. In this paper, we review progress towards effective quantitative use of STEM with illustrations drawn from studies of high Tc superconductors, compound semiconductors and metallization of H-terminated silicon.Intrinsically, STEM is a quantitative instrument. Images are acquired directly by detectors in serial mode which is particularly convenient for digital image acquisition, control and display. The VG HB501A at Cornell has been installed in a particularly stable electromagnetic, vibration and acoustic environment. Care has been paid to achieving UHV conditions (i.e., 10-10 Torr). Finally, it has been interfaced with a VAX 3200 work station by Kirkland. This permits, for example, the acquisition of bright field (or energy loss) images and dark field images simultaneously as quantitative arrays in perfect registration.

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.

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