scholarly journals Determination of the electron phonon coupling and the superconducting gap in ?-(BEDT-TTF)2X crystals (X=I3, IAuI)

1987 ◽  
Vol 68 (1) ◽  
pp. 41-47 ◽  
Author(s):  
A. Nowack ◽  
U. Poppe ◽  
M. Weger ◽  
D. Schweitzer ◽  
H. Schwenk
Keyword(s):  
Superconducting Gap ◽  
Phonon Coupling ◽  
Electron Phonon Coupling

scholarly journals Electron-Phonon Coupling Parameter of Ferromagnetic Metal Fe and Co

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2755
Author(s):  
Kyuhwe Kang ◽  
Gyung-Min Choi
Keyword(s):  
Coupling Parameter ◽  
Critical Role ◽  
Circuit Modeling ◽  
Metallic Materials ◽  
Phonon Coupling ◽  
Electron Phonon Coupling ◽  
Complicated Process ◽  
G Value ◽  
Non Equilibrium

The electron-phonon coupling (g) parameter plays a critical role in the ultrafast transport of heat, charge, and spin in metallic materials. However, the exact determination of the g parameter is challenging because of the complicated process during the non-equilibrium state. In this study, we investigate the g parameters of ferromagnetic 3d transition metal (FM) layers, Fe and Co, using time-domain thermoreflectance. We measure a transient increase in temperature of Au in an FM/Au bilayer; the Au layer efficiently detects the strong heat flow during the non-equilibrium between electrons and phonons in FM. The g parameter of the FM is determined by analyzing the temperature dynamics using thermal circuit modeling. The determined g values are 8.8–9.4 × 1017 W m−3 K−1 for Fe and 9.6–12.2 × 1017 W m−3 K−1 for Co. Our results demonstrate that all 3d transition FMs have a similar g value, in the order of 1018 W m−3 K−1.

scholarly journals Direct Determination of the Electron-Phonon Coupling Matrix Element in a Correlated System

2010 ◽  
Vol 105 (25) ◽  
Author(s):  
Huajun Qin ◽  
Junren Shi ◽  
Yanwei Cao ◽  
Kehui Wu ◽  
Jiandi Zhang ◽  
...  
Keyword(s):  
Matrix Element ◽  
Direct Determination ◽  
Phonon Coupling ◽  
Coupling Matrix ◽  
Electron Phonon Coupling

scholarly journals NONADIABATIC THEORY OF THE SUPERCONDUCTING STATE

2000 ◽  
Vol 14 (25n27) ◽  
pp. 2976-2981 ◽  
Author(s):  
MICHELA BOTTI ◽  
EMMANUELE CAPPELLUTI ◽  
CLAUDIO GRIMALDI ◽  
LUCIANO PIETRONERO
Keyword(s):  
Phonon Frequency ◽  
Superconducting Order Parameter ◽  
Charge Carriers ◽  
Superconducting Gap ◽  
Phonon Coupling ◽  
Eliashberg Theory ◽  
Frequency Scale ◽  
Electron Phonon Coupling ◽  
Normal State Properties ◽  
Nonadiabatic Effects

Fermi energies in fullerence compounds and cuprates are extremely small as consequence of the small number of charge carriers and are comparable to the phonon frequency scale. In this situation the conventional Migdal-Eliashberg theory does not hold anymore and nonadiabatic effects need to be taken into account. In previous studies, a generalization of Eliashberg theory in the nonadiabatic regime has been proposed to calculate normal state properties and the onset temperature T c of the superconductive phase. Here we extend the nonadiabatic theory below T c where the opening of the superconducting order parameter affects the nonadiabatic correction. The superconducting gap Δ is calculated in a self-consistent way. We find that large values of the ratio 2Δ/T c are obtained in the nonadiabatic theory by smaller electron-phonon coupling λ than in Migdal-Eliashberg theory. This agrees with the picture that strong-coupling phenomenology can be achieved in nonadiabatic theory by "reasonable" values of λ. We apply our analysis to the case of the fullerene compounds.

scholarly journals Determination of the electron–phonon coupling constant in tungsten

2014 ◽  
Vol 105 (2) ◽  
pp. 023112 ◽  
Author(s):  
Szymon L. Daraszewicz ◽  
Yvelin Giret ◽  
Hiroshi Tanimura ◽  
Dorothy M. Duffy ◽  
Alexander L. Shluger ◽  
...  
Keyword(s):  
Coupling Constant ◽  
Phonon Coupling ◽  
Electron Phonon Coupling

scholarly journals Optical Determination of Electron-Phonon Coupling in Carbon Nanotubes

2007 ◽  
Vol 98 (3) ◽  
Author(s):  
Y. Yin ◽  
A. N. Vamivakas ◽  
A. G. Walsh ◽  
S. B. Cronin ◽  
M. S. Ünlü ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Phonon Coupling ◽  
Electron Phonon Coupling ◽  
Optical Determination

scholarly journals The effect of strong electron-rattling phonon coupling on some superconducting properties

2019 ◽  
Vol 97 (5) ◽  
pp. 472-476
Author(s):  
Samin Tajik ◽  
Božidar Mitrović ◽  
Frank Marsiglio
Keyword(s):  
Temperature Dependence ◽  
Coupling Parameter ◽  
Nmr Relaxation ◽  
Superconducting Gap ◽  
Phonon Coupling ◽  
Phonon Modes ◽  
Strong Electron ◽  
Particle Decay ◽  
Electron Phonon Coupling ◽  
The One

Using the Eliashberg theory of superconductivity we have examined several properties of a model in which electrons are coupled only to rattling phonon modes represented by a sharp peak in the electron–phonon coupling function. Our choice of parameters was guided by experiments on β-pyrochlore oxide superconductor KOs2Os6. We have calculated the temperature dependence of the superconducting gap edge; the quasi-particle decay rate; the NMR relaxation rate assuming that the coupling between the nuclear spins and the conduction electrons is via a contact hyperfine interaction, which would be appropriate for the O-site in KOs2Os6; and the microwave conductivity. We examined the limit of very strong coupling by considering three values of the electron–phonon coupling parameter λ = 2.38, 3, and 5 and did not assume that the rattler frequency Ω0 is temperature dependent in the superconducting state. We obtained a very unusual temperature dependence of the superconducting gap edge Δ(T), very much like the one extracted from photoemission experiments on KOs2O6.

Sign in / Sign up

Export Citation Format

Share Document