Contribution of the electron-phonon interaction to the effective mass, superconducting transition temperature, and the resistivity in aluminium

1966 ◽  
Vol 4 (9) ◽  
pp. lxvi
Author(s):  
Erling Pytte
Keyword(s):  
Transition Temperature ◽  
Effective Mass ◽  
Superconducting Transition Temperature ◽  
Superconducting Transition ◽  
Phonon Interaction ◽  
Electron Phonon Interaction

ELECTRON-PHONON INTERACTION FOR AN ANALYTIC SOLUTION TO THE BCS EQUATION FOR THE HIGH TEMPERATURE SUPERCONDUCTORS

1991 ◽  
Vol 05 (20) ◽  
pp. 1349-1353 ◽  
Author(s):  
H. C. GUPTA
Keyword(s):  
High Temperature ◽  
Transition Temperature ◽  
Superconducting Transition Temperature ◽  
Analytic Solution ◽  
Energy Gap ◽  
High Temperature Superconductors ◽  
Superconducting Transition ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Gap Parameter

An energy dependent electron-phonon interaction has been used in the BCS equation. This provides an exactly solvable analytic solution to the BCS equation for the superconducting transition temperature and the gap parameter at absolute zero. These analytically obtained equations reduce to standard BCS form when temperature is small. These equations are applicable to low as well as high temperature superconductors successfully for their superconducting transition temperature and the energy gap parameter.

ELECTRON-PHONON INTERACTION, LATTICE DYNAMICS AND SUPERCONDUCTIVITY OF LAYERED TRANSITION-METAL DICHALCOGENIDE NbS2

1993 ◽  
Vol 07 (01n03) ◽  
pp. 188-192 ◽  
Author(s):  
Yoshimasa NISHIO ◽  
Masafumi SHIRAI ◽  
Naoshi SUZUKI ◽  
Kazuko MOTIZUKI
Keyword(s):  
Transition Temperature ◽  
Lattice Dynamics ◽  
Tight Binding ◽  
Transition Metal Dichalcogenide ◽  
Superconducting Transition ◽  
Lattice Instability ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Order Of Magnitude ◽  
Layered Transition Metal

Lattice dynamics of NbX 2( X = S , Se ) is studied by taking account of electron-phonon interaction derived microscopically on the basis of the realistic tight-binding bands fitted to the first-principle bands of NbX 2. Remarkable frequency renormalization of Σ1 phonon mode around [Formula: see text] is caused due to characteristic wave-vector and mode dependences of the electron-phonon interaction as well as nesting effect of Fermi surface. It is also shown that the short range force constant for neighboring X ions on different X-layers in the same X-Nb-X sandwich determines primarily whether lattice instability occurs ( NbSe 2 case) or does not occur ( NbS 2 case). By using the electron-phonon interaction and the lattice dynamics obtained for NbS 2 we have calculated the spectral function α2F(ω) and determined superconducting transition temperature T c by solving the linearlized Eliashberg equation. Renormalization of phonon frequencies due to the eletron-phonon interaction raises considerably the transition temperature and the obtained value of T c agrees in order of magnitude with the experimental data.

Far-Infrared Properties of ab plane oriented YBa2Cu3O7-δ

1987 ◽  
Vol 99 ◽  
Author(s):  
D. A. Bonn ◽  
A. H. O'Reilly ◽  
J. E. Greedan ◽  
C. V. Stager ◽  
T. Timusk ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Normal State ◽  
Superconducting State ◽  
Plasma Frequency ◽  
Far Infrared ◽  
Superconducting Transition ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Oriented Samples ◽  
Absolute Reflectance

ABSTRACTPolycrystalline samples of YBa2Cu2O7-δ with a variety of surface treatments show differences in absolute reflectance and width of phonon lines. Samples that are not polished and are measured immediately after annealing have largely grains with the c axis normal to the surface. Such oriented samples show a gap-like depression of conductivity in the far infrared that sets in below the superconducting transition temperature but no true gap. Phonon lines at 195 cm−1 and at 155 cm−1 narrow in the superconducting state, in analogy with the effect of the electron phonon interaction in BCS superconductors. In the normal state the background conductivity is Drude like with a plasma frequency of 0.75 eV and a relaxation rate of 200 cm−1. The extrapolated far-infrared conductivity agrees with the measured dc conductivity.

ELECTRON–PHONON PAIRING IN THE HUBBARD MODEL

1992 ◽  
Vol 06 (09) ◽  
pp. 541-546 ◽  
Author(s):  
N. M. PLAKIDA ◽  
V. S. UDOVENKO
Keyword(s):  
Transition Temperature ◽  
Hubbard Model ◽  
Function Technique ◽  
Superconducting Transition ◽  
Strong Correlations ◽  
Phonon Coupling ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Electron Phonon Coupling ◽  
The Green Function

A system of electrons with strong correlations is considered within the framework of a single-band Hubbard model with a strong anharmonic electron-phonon interaction. The dependence of superconducting transition temperature T c on carrier concentration n is obtained using the Green function technique. It is shown that, due to the nonlocal character of electron–phonon coupling in the model, T c (n) strongly depends on the symmetry of the gap.

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