Solution of the Eliashberg equations for a very strong electron-phonon coupling with a low-energy cutoff

1995 ◽  
Vol 507 (5) ◽  
pp. 431-450 ◽  
Author(s):  
M. Weger ◽  
B. Barbiellini ◽  
T. Jarlborg ◽  
M. Peter ◽  
G. Santi
Keyword(s):  
Low Energy ◽  
Phonon Coupling ◽  
Eliashberg Equations ◽  
Strong Electron ◽  
Electron Phonon Coupling ◽  
Energy Cutoff

THERMODYNAMIC CHARACTERISTICS OF Y–Ba–Cu–O TYPE COMPOUNDS IN THE MODEL OF STRONG ELECTRON–PHONON COUPLING

1988 ◽  
Vol 02 (05) ◽  
pp. 837-845 ◽  
Author(s):  
A. A. Golubov
Keyword(s):  
Numerical Solutions ◽  
Low Frequency ◽  
Thermodynamic Characteristics ◽  
Coupling Model ◽  
Phonon Coupling ◽  
Eliashberg Equations ◽  
Phonon Modes ◽  
Strong Electron ◽  
Phonon Spectra ◽  
Electron Phonon Coupling

Based on recently measured phonon density of states of Y–Ba–Cu–O an investigation of the strong electron-phonon coupling model is carried out. The numerical solutions of the real axis Eliashberg equations are obtained for a number of phonon spectra parameters. Isotope shifts of T c , spectral behavior of the pairing energy Δ(ω) and the ratio 2Δ g / T c (where Δ g is the gap edge) are calculated. The model gives a very small oxygen isotope shift for rather moderate values of the electron-phonon coupling constant λ ~ 3. The results strongly suggest the weak coupling with high frequency phonon modes and strong coupling with low frequency modes.

scholarly journals Structural phase transition and superconductivity hierarchy in 1T-TaS2 under pressure up to 100 GPa

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Qing Dong ◽  
Quanjun Li ◽  
Shujia Li ◽  
Xuhan Shi ◽  
Shifeng Niu ◽  
...  
Keyword(s):  
Structural Phase ◽  
Transition Metal Dichalcogenides ◽  
Phonon Coupling ◽  
Structural Phase Transitions ◽  
Strong Electron ◽  
Electron Phonon Coupling ◽  
Increasing Trend ◽  
Metal Dichalcogenides ◽  
Dome Shape ◽  
Enhanced Superconductivity

AbstractThe adoption of high pressure not only reinforces the comprehension of the structure and exotic electronic states of transition metal dichalcogenides (TMDs) but also promotes the discovery of intriguing phenomena. Here, 1T-TaS2 was investigated up to 100 GPa, and re-enhanced superconductivity was found with structural phase transitions. The discovered I4/mmm TaS2 presents strong electron–phonon coupling, revealing a good superconductivity of the nonlayered structure. The P–T phase diagram shows a dome shape centered at ~20 GPa, which is attributed to the distortion of the 1T structure. Accompanied by the transition to nonlayered structure above 44.5 GPa, the superconducting critical temperature shows an increasing trend and reaches ~7 K at the highest studied pressure, presenting superior superconductivity compared to the original layered structure. It is unexpected that the pressure-induced re-enhanced superconductivity was observed in TMDs, and the transition from a superconductor with complicated electron-pairing mechanism to a phonon-mediated superconductor would expand the field of pressure-modified superconductivity.

scholarly journals Direct observation of excitonic instability in Ta2NiSe5

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kwangrae Kim ◽  
Hoon Kim ◽  
Jonghwan Kim ◽  
Changil Kwon ◽  
Jun Sung Kim ◽  
...  
Keyword(s):  
Phase Transition ◽  
Direct Observation ◽  
Structural Phase ◽  
Temperature Phase ◽  
Phonon Coupling ◽  
Strong Electron ◽  
Weiss Temperature ◽  
Excitonic Insulator ◽  
Electron Phonon Coupling ◽  
Low Temperature Phase

AbstractCoulomb attraction between electrons and holes in a narrow-gap semiconductor or a semimetal is predicted to lead to an elusive phase of matter dubbed excitonic insulator. However, direct observation of such electronic instability remains extremely rare. Here, we report the observation of incipient divergence in the static excitonic susceptibility of the candidate material Ta2NiSe5 using Raman spectroscopy. Critical fluctuations of the excitonic order parameter give rise to quasi-elastic scattering of B2g symmetry, whose intensity grows inversely with temperature toward the Weiss temperature of TW ≈ 237 K, which is arrested by a structural phase transition driven by an acoustic phonon of the same symmetry at TC = 325 K. Concurrently, a B2g optical phonon becomes heavily damped to the extent that its trace is almost invisible around TC, which manifests a strong electron-phonon coupling that has obscured the identification of the low-temperature phase as an excitonic insulator for more than a decade. Our results unambiguously reveal the electronic origin of the phase transition.

Strong electron-phonon coupling at a metal/organic interface: PTCDA/Ag(111)

2002 ◽  
Vol 65 (12) ◽  
Author(s):  
F. S. Tautz ◽  
M. Eremtchenko ◽  
J. A. Schaefer ◽  
M. Sokolowski ◽  
V. Shklover ◽  
...  
Keyword(s):  
Phonon Coupling ◽  
Strong Electron ◽  
Electron Phonon Coupling ◽  
Metal Organic

scholarly journals Intriguing light-emission features of ketoprofen-based Eu(III) adduct due to a strong electron–phonon coupling

2016 ◽  
Vol 170 ◽  
pp. 357-363 ◽  
Author(s):  
M.G. Lahoud ◽  
R.C.G. Frem ◽  
D.A. Gálico ◽  
G. Bannach ◽  
M.M. Nolasco ◽  
...  
Keyword(s):  
Light Emission ◽  
Phonon Coupling ◽  
Strong Electron ◽  
Electron Phonon Coupling

Raman scattering from impurities in semiconductors. II. Special cases

1978 ◽  
Vol 56 (5) ◽  
pp. 560-564
Author(s):  
Robert Barrie ◽  
H. -C. Chow
Keyword(s):  
Raman Scattering ◽  
General Result ◽  
Phonon Scattering ◽  
Phonon Coupling ◽  
Strong Electron ◽  
Impurities In Semiconductors ◽  
Electron Phonon Coupling ◽  
Special Cases ◽  
Weak Electron

Special cases of the general result for Raman scattering from an impurity in a semiconductor are discussed. For weak electron–phonon coupling the zero-phonon and one-phonon scattering intensities are derived. For strong electron–phonon coupling a comparison is made between two different approximations that have been previously used.

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