scholarly journals Fermi-Bose Mixtures and BCS-BEC Crossover in High-Tc Superconductors

2019 ◽  
Vol 4 (2) ◽  
pp. 51 ◽  
Author(s):  
Maxim Yu. Kagan ◽  
Antonio Bianconi
Keyword(s):  
Room Temperature ◽  
High Tc Superconductors ◽  
High Tc ◽  
Magnetic Traps ◽  
Unconventional Superconductors ◽  
Topological Superconductors ◽  
Coupling Approach ◽  
Bose Einstein ◽  
Room Temperature Superconductivity ◽  
Twisted Graphene

In this review article we consider theoretically and give experimental support to the models of the Fermi-Bose mixtures and the BCS-BEC (Bardeen Cooper Schrieffer–Bose Einstein) crossover compared with the strong-coupling approach, which can serve as the cornerstones on the way from high-temperature to room-temperature superconductivity in pressurized metallic hydrides. We discuss some key theoretical ideas and mechanisms proposed for unconventional superconductors (cuprates, pnictides, chalcogenides, bismuthates, diborides, heavy-fermions, organics, bilayer graphene, twisted graphene, oxide hetero-structures), superfluids and balanced or imbalanced ultracold Fermi gases in magnetic traps. We build a bridge between unconventional superconductors and recently discovered pressurized hydrides superconductors H3S and LaH10 with the critical temperature close to room temperature. We discuss systems with a line of nodal Dirac points close to the Fermi surface and superconducting shape resonances, and hyperbolic superconducting networks which are very important for the development of novel topological superconductors, for the energetics, for the applications in nano-electronics and quantum computations.

Possibility of High-Tc Copper Fluoride Oxide Superconductors

1987 ◽  
Vol 99 ◽  
Author(s):  
P. T. Wu ◽  
R. S. Liu ◽  
H. M. Sung ◽  
J. H. Rung
Keyword(s):  
Solid State ◽  
Room Temperature ◽  
Complete Loss ◽  
Oxide Superconductors ◽  
High Tc ◽  
Gel Method ◽  
Loss Of Resistance ◽  
Zero Resistance ◽  
Room Temperature Superconductivity

ABSTRACTSuperconductivity of YBa2Cu3FxOy system prepared by using a mixed solid state and gel method. A consistent and non-zero resistance drop near 280K was achieved in the nominal YBa2Cu3FxOy system for x=l and 2, with complete loss of resistance at 90K. The metal-semiconductor transition occurs at x value between 2 and 3. Temporal room temperature superconductivity with zero resistance was observed in a YBa2Cu3F2Oy sample at 308K. The phenomenon lasted for three minutes and was not reproducible.

EFFECTS OF CHEMICAL DOPING AND STOICHIOMETRIC VARIATION IN HIGH-Tc SUPERCONDUCTORS

1989 ◽  
Vol 03 (04) ◽  
pp. 573-594 ◽  
Author(s):  
Y. H. KAO ◽  
Y. D. YAO ◽  
L. W. SONG
Keyword(s):  
Room Temperature ◽  
Dopant Concentration ◽  
Order Structure ◽  
Exponential Dependence ◽  
Room Temperature Resistivity ◽  
Chemical Doping ◽  
High Tc Superconductors ◽  
Host Matrix ◽  
High Tc ◽  
Temperature Resistivity

Superconducting properties of various chemically-doped high-T c materials are investigated. By using the results obtained with Cu- and Bi-deficient Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O systems as basis, variations of the transition temperature T c , critical current density J c , room temperature resistivity ρ, and oxygen content are compared for different dopant contents. In several cases, J c and ρ are found to be correlated as both quantities show an exponential dependence on the dopant concentration. Most dopants result in a monotonic decrease of T c and J c , except for Ag, F, and Cl. Substitution of Ag and Pb for Cu and Bi in Bi-Sr-Ca-Cu-O indicates a condition for compatibility between the impurity atom and the local structure in the host matrix. Results suggest that the predominant mechanism for high-T c superconductivity is most likely associated with short-range-order structure in the material.

scholarly journals PASSIVATION PROCESS OF HIGH Tc SUPERCONDUCTORS YBa2Cu3O7−δ BY FLUORINE GAS TREATMENT

1988 ◽  
Vol 02 (10) ◽  
pp. 1183-1188 ◽  
Author(s):  
A. TRESSAUD ◽  
B. CHEVALIER ◽  
B. LEPINE ◽  
J.M. DANCE ◽  
L. LOZANO ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Thin Layer ◽  
Room Temperature ◽  
Meissner Effect ◽  
Shielding Effect ◽  
High Tc Superconductors ◽  
Gas Treatment ◽  
High Tc ◽  
Exchange Processes ◽  
Atmospheric Degradation

The atmospheric degradation of high T c superconductors YBa 2 Cu 3 O 7−δ can be prevented using fluorine gas processings around room temperature. A thin layer of amorphous fluorides (and/or oxyfluorides) is formed at the surface of the particles, which passivates the material against hydrolysis and gas-exchange processes. A fluorination mechanism has been proposed, which can account for both fluorine analysis and weight uptake. The superconductivity onset does not seem to be affected by fluorination. Furthermore, an improvement of the shielding effect-Meissner effect cycle to 91% reversibility is achieved when F 2-treated oxides are heated at 350°C under vacuum.

Room Temperature Impedance and ac Conductivity Studies on Na-, K-Doped Tc-Enhanced High Tc Superconductors

2006 ◽  
Vol 19 (1-2) ◽  
pp. 143-149
Author(s):  
M. Mohammad ◽  
A. Y. Khan ◽  
M. S. Subhani ◽  
Sabahat Yasmeen ◽  
Shahnaz Malik ◽  
...  
Keyword(s):  
Ac Conductivity ◽  
Room Temperature ◽  
High Tc Superconductors ◽  
High Tc

scholarly journals Towards Room-Temperature Superconductivity

2020 ◽  
Author(s):  
Jacob Szeftel ◽  
Nicolas Sandeau ◽  
Michel Abou Ghantous ◽  
Muhammad El Saba
Keyword(s):  
Critical Temperature ◽  
Band Structure ◽  
Electron Concentration ◽  
Stability Criterion ◽  
Room Temperature ◽  
High Tc ◽  
Electron Band ◽  
Room Temperature Superconductivity ◽  
Critical Temperature Tc ◽  
Electron Band Structure

By taking advantage of a stability criterion established recently, the critical temperature Tc is reckoned with help of the microscopic parameters, characterising the normal and superconducting electrons, namely the independent-electron band structure and a repulsive two-electron force. The emphasis is laid on the sharp Tc dependence upon electron concentration and inter-electron coupling, which might offer a practical route toward higher Tc values and help to understand why high-Tc compounds exhibit such remarkable properties.

APPLICATION OF ESR TO HIGH-Tc SUPERCONDUCTORS AND RELATED MATERIALS III: CRYSTAL GROWTH RATES OF Y2BaCuO5 IN THE MELTS OF Y1+2nBa2+nCu3+nOx (n=0–0.4) SUBJECTED TO HIGH TEMPERATURES

1999 ◽  
Vol 13 (02) ◽  
pp. 51-58 ◽  
Author(s):  
K. YAMAMOTO ◽  
N. ARAI ◽  
K. HOTTA ◽  
K. SUGAWARA ◽  
H. HIROSE
Keyword(s):  
Heat Treatment ◽  
Crystal Growth ◽  
Growth Rates ◽  
Heat Treatment Temperature ◽  
Room Temperature ◽  
Atmospheric Condition ◽  
Treatment Temperature ◽  
High Tc Superconductors ◽  
Temperature Quenching ◽  
High Tc

Form the ESR measurements of Cu 2+ in Y 2 BaCuCuO 5, the growth rates of Y 2 BaCuCO 5 generated in the melts of Y 1+2n Ba 2+n Cu 3+n O x (n=0–0.4) have been quantitatively obtained as functions of heat-treatment temperature (1000–1400°C) and heat-treatment period (10–120 minutes). All the melted samples have been prepared by heating them in an atmospheric condition, and room-temperature quenching.

Sign in / Sign up

Export Citation Format

Share Document