THEORETICAL ASPECTS OF THE FIELD INDUCED SUPERCONDUCTIVITY IN POLYACENES AND C60

2002 ◽  
Vol 16 (11n12) ◽  
pp. 1547-1551
Author(s):  
S.-L. DRECHSLER ◽  
G. PAASCH ◽  
J. MÁLEK ◽  
S. V. SHULGA ◽  
H. ESCHRIG ◽  
...  
Keyword(s):  
Tight Binding ◽  
Band Structure Calculation ◽  
Full Potential ◽  
Coupling Constant ◽  
Phonon Coupling ◽  
Critical Temperatures ◽  
Binding Model ◽  
Electron Phonon Coupling ◽  
Strong Coulomb ◽  
Experimental Values

The electronic structure and the superconductivity in field-doped polyacenes are considered. Within a modified Thomas–Fermi approach for typical experimental values of the surface charge density the injected charge is confined to a monolayer. The electron–phonon coupling constant for internal modes λintra is estimated using the work of Devos and Lanoo (Ref. 4) and the density of states N(0) estimated from a 2D tight-binding model derived from a full potential LDA band structure calculation for bulk anthracene. The empirical values of the Coulomb pseudopotentials are significantly enhanced. The strong Coulomb interaction is considered as a key quantity which determines the large differences in the critical temperatures achieved for n-doped polyacenes and C 60.

The Estimate of the Electron–Phonon Coupling Constant in the Thin Film

1998 ◽  
Vol 12 (02) ◽  
pp. 177-189 ◽  
Author(s):  
M. Pantić ◽  
Lj. D. Mašković ◽  
B. S. Tošić
Keyword(s):  
Experimental Fact ◽  
Coupling Constant ◽  
Phonon Coupling ◽  
Metallic Films ◽  
Critical Temperatures ◽  
Dominant Form ◽  
Electron Phonon Interaction ◽  
Electron Phonon Coupling ◽  
Surface Electrons ◽  
Bulk Structures

Hamiltonians of electron–phonon interaction for thin metallic films are formulated. This is the basis for the estimate of the superconductivity critical temperature for films and corresponding bulk structures. It is shown that the interaction of surface electrons in the film with bulk phonons could explain the experimental fact that critical temperatures of the films are higher than the corresponding ones in bulk (massive) structures. Since above fact is valid nearly for all pure metallic, one can conclude that the dominant form or the interaction in films is the interaction of surface electrons with bulk phonons.

CROSSOVER FROM 3D TO 2D IN THE ELECTRONIC STRUCTURE OF MgB2-TYPE SYSTEMS

2002 ◽  
Vol 16 (24) ◽  
pp. 3671-3680
Author(s):  
G. Q. HUANG ◽  
M. LIU ◽  
L. F. CHEN
Keyword(s):  
Electronic Structure ◽  
Phonon Frequency ◽  
Three Dimensional ◽  
Type Systems ◽  
Orbital Method ◽  
Full Potential ◽  
Hole Density ◽  
Coupling Constant ◽  
Phonon Coupling ◽  
Electron Phonon Coupling

Using the Stuttgart Full-potential Linearized Muffin-tin Orbital method, we study a crossover of the electronic structure of MgB 2 from three-dimensional (3D) to 2D by artificially increasing the lattice constant along the c-axis. With the inter-layer coupling decreased by increasing c, the density of states (DOS) at E F has a considerable growth; at the same time, the charge transfer from Mg plane to B plane decreases so that the hole density in the B plane increases. As c is increased to 4c0, the electronic structure exhibits 2D characteristic and a van Hove peak in the DOS appears. The E2g phonon frequency at Γ point and the electron–phonon coupling constant λ are estimated by using the frozen phonon method. The calculated results indicate that T c in MgB 2 could be further increased if the inter-layer coupling might be reduced.

Size-dependence of the effective electron-phonon energy relaxation in hollow gold nanospheres

2014 ◽  
Vol 22 (1) ◽  
Author(s):  
Y. Fan ◽  
J. Li ◽  
H. Chen ◽  
X. Lu ◽  
X. Liu
Keyword(s):  
Size Dependence ◽  
Energy Relaxation ◽  
Noble Metal Nanoparticles ◽  
Coupling Constant ◽  
Phonon Coupling ◽  
Gold Nanospheres ◽  
Effective Electron ◽  
Hollow Gold Nanospheres ◽  
Electron Phonon Coupling ◽  
Experimental Values

AbstractIn this paper the size-dependence of energy relaxation, which is induced by the electron-phonon (e-ph) interactions and the electron-surface (e-s) interactions in noble metal nanoparticles, is investigated. Then based on the analysis and the derivation of the e-s coupling constant in metal nanospheres, the formula of the effective electron-phonon coupling constant Geff of hollow gold nanospheres (HGNs) is deduced. Moreover, the correctness of the formulae gets proved by contrast analyses of the calculated Geff values and experimental values obtained from literature.

scholarly journals Ab-initio studies of thermal and superconducting properties of HfX2 alloys (X = Tc, Re, and Os)

2014 ◽  
Vol 32 (3) ◽  
pp. 324-330 ◽  
Author(s):  
V. Sathyakumari ◽  
S. Sankar ◽  
K. Mahalakshmi
Keyword(s):  
Band Structure ◽  
Electronic Band Structure ◽  
Tight Binding ◽  
Coupling Constant ◽  
Phonon Coupling ◽  
Electronic Band ◽  
Atomic Sphere ◽  
Electron Phonon Coupling ◽  
Sphere Approximation ◽  
Specific Heat Coefficient

AbstractA systematic study of thermal properties such as the Debye temperature, specific heat coefficient, Grüneisen constant, electron-phonon coupling constant and transition temperature have been carried out using the results of electronic band structure and related characteristics, for hafnium superconducting alloys, namely, HfTc2, HfRe2 and HfOs2. Computation of the electronic band structure and associated properties has been carried out using the tight-binding-linear-muffin-tin-orbital (TBLMTO) method within atomic sphere approximation (ASA). The calculated values have been compared with the available results of literature data.

scholarly journals Estimation of electron-phonon coupling constant in Ba1-xKxBiO3

2020 ◽  
Vol 1686 ◽  
pp. 012049
Author(s):  
Alexander E Lukyanov ◽  
Vyacheslav D Neverov ◽  
Andrey V Krasavin ◽  
Alexey P Menushenkov
Keyword(s):  
Coupling Constant ◽  
Phonon Coupling ◽  
Electron Phonon Coupling
Sign in / Sign up

Export Citation Format

Share Document