scholarly journals ELECTRONIC BOUND STATES IN PARITY-PRESERVING QED3 APPLIED TO HIGH-Tc CUPRATE SUPERCONDUCTORS

2003 ◽  
Vol 18 (05) ◽  
pp. 725-741 ◽  
Author(s):  
H. R. CHRISTIANSEN ◽  
O. M. DEL CIMA ◽  
M. M. FERREIRA ◽  
J. A. HELAYËL-NETO
Keyword(s):  
Bound States ◽  
Cuprate Superconductors ◽  
Energy Scale ◽  
Spontaneous Breaking ◽  
Electron Interaction ◽  
Oxide Superconductors ◽  
S Wave ◽  
High Tc ◽  
Pair Condensation ◽  
Copper Oxide Superconductors

We consider a parity-preserving QED 3 model with spontaneous breaking of the gauge symmetry as a framework for the evaluation of the electron–electron interaction potential underlying high-T c superconductivity. The fact that the resulting potential, -CsK0(Mr), is non-confining and "weak" (in the sense of Kato) strongly suggests the mechanism of pair-condensation. This potential, compatible with an s-wave order parameter, is then applied to the Schrödinger equation for the sake of numerical calculations, thereby enforcing the existence of bound states. The results worked out by means of our theoretical framework are checked by considering a number of phenomenological data extracted from different copper oxide superconductors. The agreement may motivate a deeper analysis of our model viewing an application to quasiplanar cuprate superconductors. The data analyzed here suggest an energy scale of 1–10 meV for the breaking of the U(1)-symmetry.

MINIMAL ANOMALOUS OCCUPANCY IN HIGH-Tc SUPERCONDUCTIVITY

1993 ◽  
Vol 07 (24n25) ◽  
pp. 1601-1609 ◽  
Author(s):  
R.M. MÉNDEZ-MORENO ◽  
M. MORENO ◽  
S. OROZCO ◽  
M.A. ORTÍZ
Keyword(s):  
Critical Temperature ◽  
Copper Oxide ◽  
Cuprate Superconductors ◽  
Normal Limit ◽  
Good Description ◽  
Energy Scale ◽  
Oxide Superconductors ◽  
High Tc ◽  
Copper Oxide Superconductors ◽  
Fermion Gas

A study of a minimal anomalous occupancy is carried out when a small gap occurs near the Fermi surface. A limit which tends softly to the normal occupancy can be introduced. This framework is applied to a quasi-bidimensional fermion gas which can mimick the copper oxide planes in cuprate superconductors. The energy scale implied by this minimally anomalous occupancy (the soft normal limit) for high-T c cuprate superconductors is of the order of the Debye energy. Yet this anomalous occupancy framework overcomes the phonon barrier and a good description for the critical temperature of a representative set of high-T c copper oxide superconductors is obtained.

THE ENERGY GAP IN THE HIGH-Tc COPPER OXIDE SUPERCONDUCTORS

1993 ◽  
Vol 07 (03) ◽  
pp. 143-153 ◽  
Author(s):  
YONGHONG LI ◽  
CHARLES M. LIEBER
Keyword(s):  
Transition Temperature ◽  
Energy Loss ◽  
High Temperature Superconductor ◽  
Energy Gap ◽  
Low Energy ◽  
Oxide Superconductors ◽  
High Tc ◽  
Resolution Electron ◽  
Copper Oxide Superconductors ◽  
Electron Energy Loss

We briefly review high-resolution electron energy loss spectroscopy (HREELS) studies of the low energy excitations in the high-temperature superconductor Bi 2 Sr 2 CaCu 2 O 8. HREELS has been used to determine the magnitude and temperature dependence of the energy gap (2Δ) for Bi 2 Sr 2 CaCu 2 O 8 single crystals. Below the transition temperature low-energy excitations are detected in the energy loss spectra. Because the energy loss spectra are proportional to the real part of the frequency dependent resistivity, ρR(ω), the energy gap can be determined directly from the HREEL data. At low temperature 2Δ = 6kT c and Δ develops sharply for T < T c . The constraints that these new results place on potential mechanisms of superconductivity are discussed.

MERCURY-BASED SUPERCONDUCTORS WITH QUASI-NORMAL OCCUPANCY

1995 ◽  
Vol 09 (18) ◽  
pp. 1175-1184
Author(s):  
M. MORENO ◽  
R.M. MÉNDEZ-MORENO ◽  
S. OROZCO ◽  
M.A. ORTÍZ
Keyword(s):  
Transition Temperature ◽  
Fermi Surface ◽  
Weak Coupling ◽  
Cuprate Superconductors ◽  
Energy Gap ◽  
Oxide Superconductors ◽  
Coupling Constant ◽  
Effective Coupling ◽  
Small Energy ◽  
Copper Oxide Superconductors

A model with anomalous occupancy is applied to Hg-based cuprate superconductors. The anomaly consists of a small energy gap near the Fermi surface, the scale of the gap anomaly is of order of the cutoff (v.g. Debye) energy. Values of the anomalous occupancy parameters for Hg-based superconductors are obtained for different values of the ratio R and the effective coupling constant, within the weak coupling. As these materials have the highest transition temperature known for layered copper-oxide superconductors, they serve as a new testing ground for various proposed models.

Some Effects of Chemical Substitution and Applied Pressure on High Tc Copper Oxide Superconductors

1988 ◽  
pp. 29-40 ◽  
Author(s):  
M. B. Maple ◽  
Y. Dalichaouch ◽  
E. A. Early ◽  
B. W. Lee ◽  
J. T. Markert ◽  
...  
Keyword(s):  
Copper Oxide ◽  
Applied Pressure ◽  
Oxide Superconductors ◽  
High Tc ◽  
Chemical Substitution ◽  
Copper Oxide Superconductors

Possibility of cubic copper-oxide superconductors with high Tc

1991 ◽  
Vol 185-189 ◽  
pp. 1567-1568 ◽  
Author(s):  
H. Ihara ◽  
K. Bushida ◽  
N. Terada ◽  
S. Ishibashi ◽  
G. Zouganelis ◽  
...  
Keyword(s):  
Copper Oxide ◽  
Oxide Superconductors ◽  
High Tc ◽  
Copper Oxide Superconductors

Chemical substitution and pressure effects in high Tc copper oxide superconductors

1988 ◽  
Vol 153-155 ◽  
pp. 858-859 ◽  
Author(s):  
M.B. Maple ◽  
Y. Dalichaouch ◽  
E.A. Early ◽  
B.W. Lee ◽  
J.T. Markert ◽  
...  
Keyword(s):  
Copper Oxide ◽  
Pressure Effects ◽  
Oxide Superconductors ◽  
High Tc ◽  
Chemical Substitution ◽  
Copper Oxide Superconductors
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