Strain-induced modulations of electronic structure and electron–phonon coupling in dense H3S

2018 ◽  
Vol 20 (8) ◽  
pp. 5952-5957 ◽  
Author(s):  
Chang Liu ◽  
Hang Zhai ◽  
Ying Sun ◽  
Weiguang Gong ◽  
Yan Yan ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Coupling Parameter ◽  
Average Frequency ◽  
Considerable Effect ◽  
External Stress ◽  
Surface Topology ◽  
Phonon Coupling ◽  
Logarithmic Average ◽  
Electron Phonon Coupling ◽  
Fermi Surface Topology

External stress is an effective tool to modulate the Fermi surface topology, logarithmic average frequency, and electron–phonon coupling parameter of dense H3S and thus has a sensitive and considerable effect to the superconducting critical temperature.

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.

PATH-INTEGRAL APPROACH FOR ELECTRON–PHONON INTERACTION EFFECTS IN HARMONIC QUANTUM DOTS

1996 ◽  
Vol 10 (22) ◽  
pp. 2781-2796 ◽  
Author(s):  
SOMA MUKHOPADHYAY ◽  
ASHOK CHATTERJEE
Keyword(s):  
Quantum Dots ◽  
Path Integral ◽  
State Energy ◽  
Coupling Parameter ◽  
Three Dimensions ◽  
Integral Approach ◽  
Phonon Coupling ◽  
Electron Phonon Interaction ◽  
Electron Phonon Coupling ◽  
Parabolic Confinement

We use the Feynman–Haken path-integral formalism to obtain the polaronic correction to the ground state energy of an electron in a polar semiconductor quantum dot with parabolic confinement in both two and three dimensions. We perform calculations for the entire range of the electron–phonon coupling parameter and for arbitrary confinement length. We apply our results to several semiconductor quantum dots and show that the polaronic effect in some of these dots can be considerably large if the dot sizes are made smaller than a few nanometers.

scholarly journals Highly-Tunable Crystal Structure and Physical Properties in FeSe-Based Superconductors

Crystals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 560 ◽  
Author(s):  
Kaiyao Zhou ◽  
Junjie Wang ◽  
Yanpeng Song ◽  
Liwei Guo ◽  
Jian-gang Guo
Keyword(s):  
Crystal Structure ◽  
Electronic Structure ◽  
Critical Role ◽  
Phonon Coupling ◽  
Inorganic Layer ◽  
Chemical Substitution ◽  
Electron Phonon Coupling ◽  
Carrier Doping ◽  
Critical Temperature Tc ◽  
Fese Superconductors

Here, crystal structure, electronic structure, chemical substitution, pressure-dependent superconductivity, and thickness-dependent properties in FeSe-based superconductors are systemically reviewed. First, the superconductivity versus chemical substitution is reviewed, where the doping at Fe or Se sites induces different effects on the superconducting critical temperature (Tc). Meanwhile, the application of high pressure is extremely effective in enhancing Tc and simultaneously induces magnetism. Second, the intercalated-FeSe superconductors exhibit higher Tc from 30 to 46 K. Such an enhancement is mainly caused by the charge transfer from the intercalated organic and inorganic layer. Finally, the highest Tc emerging in single-unit-cell FeSe on the SrTiO3 substrate is discussed, where electron-phonon coupling between FeSe and the substrate could enhance Tc to as high as 65 K or 100 K. The step-wise increment of Tc indicates that the synergic effect of carrier doping and electron-phonon coupling plays a critical role in tuning the electronic structure and superconductivity in FeSe-based superconductors.

Electron-Phonon Coupling in Superconducting Alkali-Metal Doped Fullerenes

1992 ◽  
Vol 270 ◽  
Author(s):  
R.A. Jishi ◽  
M.S. Dresseliiaus
Keyword(s):  
Experimental Data ◽  
Alkali Metal ◽  
Phonon Mode ◽  
Coupling Parameter ◽  
Tight Binding ◽  
Superconducting Transition ◽  
Phonon Coupling ◽  
Doped Fullerenes ◽  
Electron Phonon Coupling ◽  
Metal Doped

ABSTRACTThe dimensionless electron-phonon coupling parameter in alkali metal-doped fullerenes isevaluated in a model whereby the electrons are treated within a tight binding formalism.The phonon mode frequencies and eigenvectors are obtained from a lattice dynamical modelwhich accurately fits all available experimental data on these modes. It is shown that the electrormphonon interaction can account for the relatively high values of the superconducting transition temperatures in alkali-metal fullerenes.

scholarly journals Electronic structure and electron-phonon coupling of doped graphene layers inKC8

2009 ◽  
Vol 79 (20) ◽  
Author(s):  
A. Grüneis ◽  
C. Attaccalite ◽  
A. Rubio ◽  
D. V. Vyalikh ◽  
S. L. Molodtsov ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Phonon Coupling ◽  
Graphene Layers ◽  
Electron Phonon Coupling ◽  
Doped Graphene

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.

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