ELECTRON-PHONON INTERACTION AND SUPERCONDUCTIVITY IN OXIDE SUPERCONDUCTORS La2−xSrxCuO4

1993 ◽  
Vol 07 (01n03) ◽  
pp. 182-185
Author(s):  
M. SHIRAI ◽  
T. KINOSHITA ◽  
K. MOTIZUKI
Keyword(s):  
Tight Binding ◽  
Wide Energy Range ◽  
Oxide Superconductors ◽  
Tunneling Conductance ◽  
Eliashberg Equations ◽  
Phonon Modes ◽  
Phonon Interaction ◽  
Characteristic Structure ◽  
Electron Phonon Interaction ◽  
Wide Energy

Effects of electron-phonon interaction on lattice dynamics in oxide superconductors La 2−x Sr x CuO 4 (LSC) are studied microscopically on the basis of the tight-binding band fitted to the first principle band. Breathing-type vibrations of oxygen atoms in the CuO 2 plane are renormalized significantly at around (π/a, π/a, 0) and (π/a, 0, 0) due to strong dependences of the electron-phonon interaction on wavevectors and phonon modes. In the framework of the usual phonon-mediated pairing mechanism, superconducting properties, such as transition temperatures and tunneling spectra, are studied by solving isotropic Eliashberg equations. The spectral function α2F(ω) has a characteristic structure over a wide energy range below 85 meV. The tunneling conductance d I/ d V and its derivative d 2I/ d V2 calculated have prominent peaks below 40 meV, which show good correspondences to those observed by recent tunneling experiments.

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.

scholarly journals Многократное изменение электрон-фононного взаимодействия в квантовых ямах с диэлектрически различными барьерами

2022 ◽  
Vol 56 (1) ◽  
pp. 101
Author(s):  
А.Ю. Маслов ◽  
О.В. Прошина
Keyword(s):  
Quantum Wells ◽  
Charged Particles ◽  
Strong Interactions ◽  
Asymmetric Structure ◽  
Optical Phonons ◽  
Phonon Modes ◽  
Phonon Interaction ◽  
Barrier Materials ◽  
Electron Phonon Interaction ◽  
Order Of Magnitude

Abstract The specific features of the interaction of charged particles with polar optical phonons have been studied theoretically for quantum wells with the barriers that are asymmetric in their dielectric properties. It is shown that the interaction with interface phonon modes makes the greatest contribution in narrow quantum wells. The parameters of the electron-phonon interaction were found for the cases of different values of the phonon frequencies in the barrier materials. It turned out that a significant (by almost an order of magnitude) change in the parameters of the electron-phonon interaction can occur in such structures. This makes it possible, in principle, to trace the transition from weak to strong interactions in quantum wells of the same type but with different compositions of barrier materials. The conditions are found under which an enhancement of the electron-phonon interaction is possible in an asymmetric structure in comparison with a symmetric one with the barriers of the same composition.

OPTICAL REFLECTIVITY STUDY ON THE SINGLE CRYSTALLINE (La1−xSrx)2CuO4

1988 ◽  
Vol 01 (09n10) ◽  
pp. 353-361 ◽  
Author(s):  
S. TAJIMA ◽  
S. UCHIDA ◽  
H. ISHII ◽  
H. TAKAGI ◽  
S. TANAKA ◽  
...  
Keyword(s):  
Infrared Spectrum ◽  
Energy Range ◽  
Single Crystal ◽  
Phonon Spectrum ◽  
Wide Energy Range ◽  
Phonon Modes ◽  
Single Crystalline ◽  
Optical Reflectivity ◽  
Reflectivity Spectra ◽  
Wide Energy

The optical reflectivity spectra were measured for single crystalline La2CuO4 and La1.8Sr0.2CuO4 over a wide energy range from 12meV to 3eV. Comparing the phonon spectrum of single crystal with that of polycrystal, the observed four phonon modes can be classified into the two—the vibrations parallel and perpendicular to the c-axis. The infrared spectrum of La1.8Sr0.2CuO4 shows the normal Drude-type behavior without any extra excitation.

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