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.

ELECTRON-PHONON INTERACTION IN TERNARY SILICIDES MGaSi (M=Ca, SrandBa)

2005 ◽  
Vol 19 (01n03) ◽  
pp. 163-165
Author(s):  
G. Q. HUANG ◽  
L. F. CHEN
Keyword(s):  
Density Functional ◽  
Striking Feature ◽  
Full Potential ◽  
Superconducting Transition ◽  
Phonon Coupling ◽  
Potential Density ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Phonon Spectra ◽  
Electron Phonon Coupling

The electron-phonon (EP) interaction in ternary silicides M GaSi with M= Ca , Sr and Ba are calculated using the full potential, density-functional-based method. A striking feature of the phonon spectra is the existence of very soft " B 1g" mode, which is strong anharmonic and plays an important role in superconductivity of the M GaSi compounds. The superconducting transition temperatures Tc in these compounds have been evaluated. It is found that the variation trend in Tc can be explained from the strength of the electron-phonon coupling.

INFLUENCE OF ELECTRON–PHONON INTERACTION ON EFFECTIVE MASS IN SOME HEAVY FERMION (HF) SYSTEMS

2008 ◽  
Vol 22 (04) ◽  
pp. 365-379 ◽  
Author(s):  
S. MOHANTY ◽  
B. K. KALTA ◽  
P. NAYAK
Keyword(s):  
Effective Mass ◽  
Coupling Strength ◽  
Heavy Fermion ◽  
Simple Expression ◽  
Model Parameters ◽  
Coupling Mechanism ◽  
Phonon Coupling ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Electron Phonon Coupling

It is a fact that for ordinary metals, the electron–phonon interaction increases the quasi-particle mass, which is in contrast to the finding by Fulde et al. that, for some heavy Fermion (HF) systems, it decreases. Some experiments on HF systems suggest that there exists a strong coupling of the elastic degrees of freedom with these at the electronic and magnetic ones. To understand the effect of electron–phonon interaction on effective mass, the electron–phonon coupling mechanism in the framework of the periodic Anderson model is considered, and a simple expression is derived. This involves various model parameters namely, the position of the 4f level; the effective coupling strength, g, temperature, b; and the electron–phonon coupling strength, r. The influence of these parameters on the value of effective mass is studied, and interesting results were found. For simplicity, the numerical calculation is performed in the long wavelength limit.

EFFECTS OF ELECTRON–PHONON INTERACTION IN TUNNELING PROCESSES IN NANOSTRUCTURES

2007 ◽  
Vol 06 (05) ◽  
pp. 411-414
Author(s):  
P. I. ARSEYEV ◽  
N. S. MASLOVA
Keyword(s):  
Phonon Coupling ◽  
Phonon Interaction ◽  
Strong Electron ◽  
Resonant Case ◽  
Electron Phonon Interaction ◽  
Electron Phonon Coupling ◽  
Tunneling Conductivity ◽  
Nonequilibrium Effects ◽  
Inelastic Tunneling

Tunneling through a system with two discrete electron levels coupled by electron–phonon interaction is considered. The interplay between elastic and inelastic tunneling channels is analyzed for a strong electron–phonon coupling in the resonant case. It is shown that the intensity and the width of peaks in tunneling conductivity are strongly influenced by nonequilibrium effects.

A First-Principles Study of Electron-Phonon Coupling of OsB2

2014 ◽  
Vol 597 ◽  
pp. 113-116
Author(s):  
Yue Qin Wang ◽  
Juan Gao ◽  
Shao Ping Yan
Keyword(s):  
Transition Temperature ◽  
First Principles ◽  
Linear Response ◽  
Lattice Dynamics ◽  
Superhard Material ◽  
Superconducting Transition ◽  
Phonon Coupling ◽  
Phonon Modes ◽  
Electron Phonon Coupling ◽  
Coulomb Pseudopotential

We investigated the lattice dynamics and electron-phonon coupling (EPC) of superhard material OsB2by first-principles linear response calculations. The calculated EPC parameters for the optical phonon modes at Г indicate that the heavy Os atoms play the most important role in deciding the superconducting behavior, and there are sizeable contributions from lighter B atoms to EPC. Our calculated EPC constant is 0.42, and the estimated superconducting transition temperatureTcis 2.1 K using the Coulomb pseudopotentialμ*=0.125, in excellent agreement with the experimental ones.

Investigations of the Thermal Shifts and Electron–Phonon Coupling Parameters of R1 and R2 Lines for Cr3+-doped Forsterite

2014 ◽  
Vol 69 (8-9) ◽  
pp. 497-500 ◽  
Author(s):  
Xiao-Xuan Wu ◽  
Wen-Chen Zheng
Keyword(s):  
Thermal Expansion ◽  
Spectral Lines ◽  
Coupling Coefficients ◽  
Phonon Coupling ◽  
Lattice Thermal Expansion ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Electron Phonon Coupling ◽  
Coupling Parameters ◽  
Vibrational Contribution

The thermal shifts of R1 and R2 lines in Cr3+-doped forsterite (Mg2SiO4) are studied by considering both the static contribution due to lattice thermal expansion and the vibrational contribution due to electron-phonon interaction. In the studies, the thermal expansion coefficient of the Cr3+ center is assumed reasonably as that of the corresponding cluster in the host crystal. The results suggest that for R1 and R2 lines the static contributions are opposite in sign and in magnitude about 37% and 45%, respectively, of the corresponding vibrational contributions. The true electron-phonon coupling coefficients α' (obtained by considering both contributions) increase by about 58% and 81%, respectively, for R1 and R2 lines in comparison with the corresponding parameters α obtained by considering only the vibrational contribution. It appears that for the reasonable explanation of thermal shift of spectral lines and the exact estimation of electron-phonon coupling coefficient, both the static and vibrational contributions should be taken into account

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