Tuning of the Fermi level at the second subband of a superlattice of quantum wires in the CuO2 plane: A possible mechanism to raise the critical temperature

AbstractBy analyzing structural and electronic properties of more than a hundred predicted hydrogen-based superconductors, we determine that the capacity of creating an electronic bonding network between localized units is key to enhance the critical temperature in hydrogen-based superconductors. We define a magnitude named as the networking value, which correlates with the predicted critical temperature better than any other descriptor analyzed thus far. By classifying the studied compounds according to their bonding nature, we observe that such correlation is bonding-type independent, showing a broad scope and generality. Furthermore, combining the networking value with the hydrogen fraction in the system and the hydrogen contribution to the density of states at the Fermi level, we can predict the critical temperature of hydrogen-based compounds with an accuracy of about 60 K. Such correlation is useful to screen new superconducting compounds and offers a deeper understating of the chemical and physical properties of hydrogen-based superconductors, while setting clear paths for chemically engineering their critical temperatures.

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The possibilities of critical temperature (T/sub c/) increasing in nanotubes with the properties of quantum wires

2001 Siberian Russian Student Workshop on Electron Devices and Materials. Proceedings 2nd Annual (IEEE Cat. No.01EX469) ◽

10.1109/sredm.2001.939166 ◽

2002 ◽

Author(s):

R.F. Khusnutdinov ◽

A.S. Berdinsky

Keyword(s):

Critical Temperature ◽

Quantum Wires

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SUPERSTRIPES

International Journal of Modern Physics B ◽

10.1142/s0217979200003769 ◽

2000 ◽

Vol 14 (29n31) ◽

pp. 3289-3297 ◽

Cited By ~ 71

Author(s):

A. BIANCONI

Keyword(s):

Critical Temperature ◽

Fermi Level ◽

Critical Point ◽

Room Temperature ◽

Quantum Critical Point ◽

Single Electrons ◽

Self Organized ◽

Atomic Limit ◽

De Broglie Wavelength ◽

Short Time

A superconducting superlattice of quantum stripes with a particular shape that gives the amplification of the critical temperature is called "superstripes". This superlattice is characterized by: a) the metallic stripe width L of the order of the de Broglie wavelength of electrons at the Fermi level, L ~λ F , and b) the hopping of pairs between the stripes larger than the hopping of single electrons. "Superstripes" can be realized artificially to get new room temperature superconductors (RTS). This particular mesoscopic heterostructure at the atomic limit has been found as a self organized network of charges, in a short time and space scale, in doped cuprate perovskites near the micro-strain quantum critical point for "superstripes" formation.

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Tuning of the Fermi level at the shape resonance in a superlattice of quantum wires: a mechanism for high Tc

10.1117/12.241741 ◽

1996 ◽

Author(s):

Antonio Bianconi ◽

A. Lanzara ◽

A. Perali ◽

T. Rossetti ◽

N. L. Saini ◽

...

Keyword(s):

Fermi Level ◽

Quantum Wires ◽

Shape Resonance ◽

High Tc

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MAGNETISM, PHONONS AND ANISOTROPY OF HIGH TEMPERATURE CUPRATES SUPERCONDUCTORS

International Journal of Modern Physics B ◽

10.1142/s0217979201004678 ◽

2001 ◽

Vol 15 (05) ◽

pp. 511-526 ◽

Cited By ~ 10

Author(s):

JACQUES FRIEDEL ◽

MAHITO KOHMOTO

Keyword(s):

High Temperature ◽

Critical Temperature ◽

Fermi Level ◽

Density Of States ◽

Hole Doping ◽

Magnetic Fluctuations ◽

Phonon Coupling ◽

High Critical Temperature ◽

Bloch Functions ◽

Gap Anisotropy

Phonon or electron mediated weak BCS attraction is enough to have high critical temperature if a van Hove anomaly is at work. This could apply to electron doped compounds and also to compounds with CuO 2 planes overdoped in holes, where T c decreases with increasing doping. If phonons dominate, it should lead to an anisotropic but mainly s superconductive gap, as observed recently in overdoped LaSrCuO, and probably also in electron doped compounds. If electrons dominate, a d-gap should develop as observed in a number of cases. In the underdoped range, the observed decrease of T c with hole doping can be related in all cases to the development of antiferromagnetic fluctuations which produces a magnetic pseudogap, thus lowering the density of states at the Fermi level. The observed mainly d-superconductive gap then can be due to a prevalent superconductive coupling through antiferromagnetic fluctuations; it could also possibly be attributed to the same phonon coupling as in the overdoped range, now acting on Bloch functions scattered in the magnetic pseudogap. More systematic studies of superconductive gap anisotropy and of magnetic fluctuations would be in order.

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MAGNETIC PROPERTIES OF Ti-Co SOLID SOLUTIONS

Modern Physics Letters B ◽

10.1142/s0217984999000312 ◽

1999 ◽

Vol 13 (08) ◽

pp. 233-238

Author(s):

IULIU POP ◽

OLIVIA POP

Keyword(s):

Phase Diagram ◽

Magnetic Properties ◽

Magnetic Susceptibility ◽

Critical Temperature ◽

Fermi Level ◽

Solid Solutions ◽

Magnetic Phase ◽

Magnetic Phase Diagram ◽

Main Mechanism ◽

Thermal Variation

Thermal variation of the magnetic susceptibility for Ti-Co solid solutions is reported. Cobalt, by alloying acts on the transition Néel temperature giving rise to a complicated magnetic phase diagram. The change of the Fermi level is the main mechanism in the critical temperature, T N , shift.

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RECENT RESEARCH RELATED TO THE MECHANISM OF HIGH-Tc SUPERCONDUCTIVITY

International Journal of Modern Physics B ◽

10.1142/s021797928800113x ◽

1988 ◽

Vol 02 (05) ◽

pp. 1273-1291 ◽

Cited By ~ 4

Author(s):

H. Katayama-Yoshida ◽

T. Takahashi ◽

H. Matsuyama ◽

Y. Okabe ◽

Y. Kitaoka ◽

...

Keyword(s):

Fermi Level ◽

Lattice Relaxation ◽

Cuo2 Plane ◽

Spin Lattice Relaxation ◽

Superconducting Transition ◽

S Wave ◽

High Tc ◽

High Tc Superconductivity ◽

Spin Lattice ◽

Nmr Study

For the understanding of the mechanism of high-Tc suuperconductivity, (i). We determined the band structure of single crystal of Bi2Sr2CaCu2O8 by angle-resolved resonant photoemission experiment. Two dispersive bands with mainly oxygen 2p character were observed in the vicinity of the Fermi level and one of them crosses the Fermi level. This result shows the direct evidence of the Fermi-liquid states with oxygen 2p character. (ii). We performed NMR study of enriched 17 O in the CuO2 plane of the superconducting Y-Ba-Cu-O system. We found BCS-like enhancement of 17 O nuclear spin-lattice, relaxation rate 1/T1 below Tc. This shows an evidence that the high-Tc superconductivity is of s-wave type with oxygen p-hole Cooper pairing. (iii). We observed an oxygen isotope shift in Bi-Sr-Ca-Cu-O superconductors when 18 O is substituted for 16 O . The superconducting transition temperature Tc is lowered by about 0.32 K for the higher-Tc phase (Tc = 110K) and by about 0.34 K for the lower-Tc phase (Tc = 75K). These results show the evidence of a measurable contribution to the superconductivity from phonons.

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