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.

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.

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.

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

ELASTIC PROPERTIES OF THE Zn SUBSTITUTED ErBa2Cu3O7-δ SUPERCONDUCTOR

2003 ◽  
Vol 17 (02) ◽  
pp. 75-82
Author(s):  
T. V. CHONG ◽  
R. ABD-SHUKOR
Keyword(s):  
Longitudinal Velocity ◽  
Shear Velocity ◽  
Spin Correlation ◽  
Coupling Constant ◽  
Phonon Coupling ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Electron Phonon Coupling ◽  
Overlap Method ◽  
Pulse Echo

Ultrasonic longitudinal and shear velocity in superconducting ErBa 2( Cu 3-x Zn x) O 7-δ (x = 0, 0.01 and 0.05) have been measured using the pulse-echo-overlap method at frequency 5–10 MHz in the temperature range 80–300 K. Longitudinal velocity hysteresis and elastic anomaly were observed in the x = 0 sample. Similar hysteresis was not observed in the x = 0.01 and 0.05 samples. The characteristic Debye temperature and electron–phonon coupling constant were calculated. The absence of hysteresis for longitudinal velocity in the x = 0.01 and 0.05 samples may be due to the spin correlation at the CuO 2 planes which affects the electron–phonon interaction.

scholarly journals Impact of electron–phonon coupling on electron transport through T-shaped arrangements of quantum dots in the Kondo regime

2021 ◽  
Vol 12 ◽  
pp. 1209-1225
Author(s):  
Patryk Florków ◽  
Stanisław Lipiński
Keyword(s):  
Quantum Dots ◽  
Mean Field ◽  
Strongly Correlated ◽  
Interference Effects ◽  
Phonon Coupling ◽  
Many Body ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Kondo Effects ◽  
Electron Phonon Coupling

We calculate the conductance through strongly correlated T-shaped molecular or quantum dot systems under the influence of phonons. The system is modelled by the extended Anderson–Holstein Hamiltonian. The finite-U mean-field slave boson approach is used to study many-body effects. Phonons influence both interference and correlations. Depending on the dot unperturbed energy and the strength of electron–phonon interaction, the system is occupied by a different number of electrons that effectively interact with each other repulsively or attractively. This leads, together with the interference effects, to different spin or charge Fano–Kondo effects.

scholarly journals Measuring the Electron–Phonon Interaction in Two-Dimensional Superconductors with He-Atom Scattering

2020 ◽  
Vol 5 (4) ◽  
pp. 79
Author(s):  
Giorgio Benedek ◽  
Joseph R. Manson ◽  
Salvador Miret-Artés ◽  
Adrian Ruckhofer ◽  
Wolfgang E. Ernst ◽  
...  
Keyword(s):  
Enhancement Factor ◽  
Coupling Constants ◽  
Phonon Coupling ◽  
Phonon Interaction ◽  
Helium Atom Scattering ◽  
Electron Phonon Interaction ◽  
Atom Scattering ◽  
Electron Phonon Coupling ◽  
Layered Transition Metal ◽  
Mass Enhancement

Helium-atom scattering (HAS) spectroscopy from conducting surfaces has been shown to provide direct information on the electron–phonon interaction, more specifically the mass-enhancement factor λ from the temperature dependence of the Debye–Waller exponent, and the mode-selected electron–phonon coupling constants λQν from the inelastic HAS intensities from individual surface phonons. The recent applications of the method to superconducting ultra-thin films, quasi-1D high-index surfaces, and layered transition-metal and topological pnictogen chalcogenides are briefly reviewed.

Dynamical Jahn-Teller Systems: Internal Energy Resonance Structures of Isolated Jahn-Teller Molecules (E-b and T-t System)

1981 ◽  
Vol 36 (7) ◽  
pp. 685-693
Author(s):  
E. Sigmund ◽  
S. Brühl
Keyword(s):  
Phonon Coupling ◽  
Phonon Interaction ◽  
Resonance Structures ◽  
Energy Resonance ◽  
Electron Phonon Interaction ◽  
Transfer Processes ◽  
Electron Phonon Coupling ◽  
Jahn Teller ◽  
Coupling Strengths ◽  
T System

Abstract The internal energetic transfer processes of an E - b and T - t Jahn-Teller system are con­ sidered. The first system allows an exact description, whereas in the case of the second one ap­ proximations must be introduced in the region of intermediate electron-phonon coupling strengths. The occupation probabilities of the states of the uncoupled systems change with time by virtue of the electron-phonon interaction. The energies are directly related to these occupation probabilities. The resonant nature of the T - t system is reflected in the internal dynamics of the latter.

ELECTRONIC STRUCTURE AND ELECTRON-PHONON INTERACTION FOR La2-xMxCuO4 SYSTEMS

1987 ◽  
Vol 01 (03n04) ◽  
pp. 951-955 ◽  
Author(s):  
A.A. Aligia ◽  
K.H. Bennemann ◽  
M. Kulić ◽  
V. Zlatić
Keyword(s):  
Electronic Structure ◽  
Tight Binding ◽  
Relative Importance ◽  
Binding Theory ◽  
Phonon Coupling ◽  
Phonon Modes ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Electron Phonon Coupling

The electronic properties and the electron-phonon coupling in La2-xMxCuO4 type compounds are studied within the tight-binding theory. Derived expressions for electron-phonon coupling exhibit clearly the relative importance of various phonon modes. The possible role of the breathing type oxygen vibrations in the electronically driven lattice instabilities and superconductivity is discussed as a function of the impurity concentration.

Strong electron–phonon interaction retarding phonon transport in superconducting hydrogen sulfide at high pressures

2018 ◽  
Vol 20 (37) ◽  
pp. 24222-24226 ◽  
Author(s):  
Jia-Yue Yang ◽  
Ming Hu
Keyword(s):  
Hydrogen Sulfide ◽  
High Pressures ◽  
Phonon Transport ◽  
Ultrahigh Pressure ◽  
Phonon Coupling ◽  
Phonon Interaction ◽  
Strong Electron ◽  
Interatomic Distances ◽  
Electron Phonon Interaction ◽  
Electron Phonon Coupling

Ultrahigh pressure greatly shortens interatomic distances and induces strong electron–phonon coupling that significantly reduces the phonon transport of superconducting H3S.

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