Journal ArticleDOI
Nonadiabatic superconductivity: electron phonon interaction beyond Migdal's theorem
Luciano Pietronero,P. Benedetti,P. Benedetti,Emmanuele Cappelluti,Claudio Grimaldi,Sigfrid Strässler,Georgios Varelogiannis +6 more
TLDR
In this article, a generalization of the usual BCS-Eliashberg scheme to include non-adiabatic effects beyond Migdal's Theorem is proposed. But the main results, the possible lines of development and the main open problems are discussed.Abstract:
A common characteristic of all the high Tc materials, oxides and Fullerene compounds, is that the Fermi energy is much smaller than in usual metals and it is of the order of the Debye phonon frequencies. This requires a generalization of the usual BCS-Eliashberg scheme to include non adiabatic effects beyond Migdal's Theorem. We have developed the first steps of this generalization and here we discuss the main results, the possible lines of development and the main open problems. The key point is that the first order non adiabatic effects (vertex corrections and similar processes) depend crucially on the momentum (q) of the exchanged phonons. If small q scattering is predominant, one obtains a strong enhancement of Tc and various other effecs also for the normal state that should lead to precise experimental predictions. The predominance of small q scattering can be naturally obtained from electronic correlations but it could arise also from different properties like peaks in the density of states.read more
Citations
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A perspective on conventional high-temperature superconductors at high pressure: Methods and materials
TL;DR: In this paper, the authors provide an up-to-date compendium of the available results on superconducting hydrides and explain how the synergy of different methodologies led to extraordinary discoveries in the field.
Journal ArticleDOI
Superconductivity mediated by polar modes in ferroelectric metals.
C. Enderlein,C. Enderlein,J. Ferreira de Oliveira,D. A. Tompsett,E. Baggio Saitovitch,Siddharth S. Saxena,Siddharth S. Saxena,Gilbert G. Lonzarich,S. E. Rowley +8 more
TL;DR: A quantitative model involving the dynamical screening of the Coulomb interaction is presented and it is found that an enhancement of Tc near to a ferroelectric quantum critical point can arise due to the virtual exchange of longitudinal hybrid-polar-modes, even in the absence of a strong coupling to the transverse critical modes.
Journal ArticleDOI
Electron and phonon dispersions of the two-dimensional Holstein model: effects of vertex and non-local corrections
TL;DR: In this paper, a dynamical cluster approximation is applied to the calculation of electron and phonon dispersions in the two-dimensional Holstein model, which enables the effects of spatial fluctuations (non-local corrections) to be examined.
Journal ArticleDOI
Electron-polaron dichotomy of charge carriers in perovskite oxides
Marius-Adrian Husanu,Lorenzo Vistoli,Carla Verdi,Carla Verdi,Anke Sander,Vincent Garcia,Julien E. Rault,Federico Bisti,L. L. Lev,Thorsten Schmitt,Feliciano Giustino,Feliciano Giustino,Andrey S. Mishchenko,Andrey S. Mishchenko,Manuel Bibes,Vladimir N. Strocov +15 more
TL;DR: In this article, angle-resolved photoelectron spectroscopy was used to investigate changes in charge carrier properties and electron-phonon interactions as a function of Ce-doping across the metal-insulator transition in CaMnO3.
Journal ArticleDOI
Study of layered superconductors in the framework of an electron–phonon coupling mechanism
TL;DR: In this article, a number of recent developments in the study of layered superconductors using the electron-phonon Eliashberg theory were summarized and the critical temperature was calculated using the theory.
References
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Journal ArticleDOI
Possible high Tc superconductivity in the Ba-La-Cu-O system
TL;DR: In this paper, Ba−La−Cu−O system, with the composition BaxLa5−xCu5O5(3−y) have been prepared in polycrystalline form, and samples with x=1 and 0.75,y>0, annealed below 900°C under reducing conditions, consist of three phases, one of them a perovskite-like mixed-valent copper compound.
Journal ArticleDOI
Superconductivity in narrow-band systems with local nonretarded attractive interactions
TL;DR: In this paper, the authors review the thermodynamic and electromagnetic properties of such systems in several limiting scenarios: (i) systems with on-site pairing which can be described by the extended negative-$U$ Hubbard model, at which it reduces to a system of tightly bound electron pairs (bipolarons) on a lattice, and the changeover from weak-attraction BCS-like superconductivity to the superfluidity of charged hard core bosons is examined.
Journal ArticleDOI
Basic similarities among cuprate, bismuthate, organic, Chevrel-phase, and heavy-fermion superconductors shown by penetration-depth measurements.
Yohei Uemura,L. P. Le,Graeme Luke,B. J. Sternlieb,Wenjing Wu,Jess H. Brewer,T. M. Riseman,C. L. Seaman,M. B. Maple,Masayasu Ishikawa,D. G. Hinks,James D. Jorgensen,Gunzi Saito,Hideki Yamochi +13 more
TL;DR: Muon-spin-relaxation and bulk measurements of the magnetic-field penetration depth suggest that the cuprate high-{ital T}{sub {ital c}}, bismuthate, organic Chevrel-phase, and heavy-fermion systems possibly belong to a unique group of superconductors characterized by high transition temperatures.
Journal ArticleDOI
Normal He 3 : an almost localized Fermi liquid
TL;DR: In this article, a variational approach to the Hubbard model is employed to calculate static properties of normal-liquid at T = 0, and the results of this method, obtained by Brinkman and Rice for the metal-insulator transition in the case of one particle per site, appear to be in qualitative agreement with the experimentally measured properties of that liquid.
Journal ArticleDOI
Superconductivity in the fullerenes.
TL;DR: It is predicted that high frequency H2 modes acquire a width of about 20% of their frequency in superconductive fullerenes, and soften by about 5% compared to the insulating fullererenes.
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