scholarly journals Efficient method to calculate the electron–phonon coupling constant and superconducting transition temperature

2017 ◽  
Vol 220 ◽  
pp. 239-242 ◽  
Author(s):  
Takashi Koretsune ◽  
Ryotaro Arita
Keyword(s):  
Transition Temperature ◽  
Efficient Method ◽  
Superconducting Transition Temperature ◽  
Superconducting Transition ◽  
Coupling Constant ◽  
Phonon Coupling ◽  
Electron Phonon Coupling

H Implantation Improves Superconductivity in Non-Transition Metals

1983 ◽  
Vol 27 ◽  
Author(s):  
F. Ochmann ◽  
B. Stritzker
Keyword(s):  
Transition Temperature ◽  
Transition Metals ◽  
Superconducting Transition Temperature ◽  
Radiation Effects ◽  
Superconducting Transition ◽  
Coupling Constant ◽  
Phonon Coupling ◽  
Electron Phonon Coupling ◽  
Host Metal

ABSTRACTThe superconducting transition temperature, Tc, of a series of non-transition metals was improved by implantation of H and D into these metals kept below 10 K. In all cases the increase of Tc was considerably larger for H and D implantation with respect of He implantation causing only radiation effects. It could be shown that the enhancement of Tc depends on the electron-phonon coupling constant of the host metal, suggesting that mainly phonon effects dominate the improvement of Tc.

scholarly journals Unconventional Co-Existence of Insulating Nano-Regions and Conducting Filaments in Reduced SrTiO3: Mode Softening, Local Piezoelectricity, and Metallicity

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 437
Author(s):  
Annette Bussmann-Holder ◽  
Hugo Keller ◽  
Arndt Simon ◽  
Gustav Bihlmayer ◽  
Krystian Roleder ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Carrier Concentration ◽  
Superconducting Transition Temperature ◽  
Superconducting Transition ◽  
First Principles Calculations ◽  
Effective Electron ◽  
Mode Softening ◽  
Component Type ◽  
Electron Phonon Coupling ◽  
Transverse Optic

Doped SrTiO3 becomes a metal at extremely low doping concentrations n and is even superconducting at n < 1020 cm−3, with the superconducting transition temperature adopting a dome-like shape with increasing carrier concentration. In this paper it is shown within the polarizability model and from first principles calculations that up to a well-defined carrier concentration nc transverse optic mode softening takes place together with polar nano-domain formation, which provides evidence of inhomogeneity and a two-component type behavior with metallicity coexisting with polarity. Beyond this region, a conventional metal is formed where superconductivity as well as mode softening is absent. For n ≤ nc the effective electron-phonon coupling follows the superconducting transition temperature. Effusion measurements, as well as macroscopic and nanoscopic conductivity measurements, indicate that the distribution of oxygen vacancies is local and inhomogeneous, from which it is concluded that metallicity stems from filaments which are embedded in a polar matrix as long as n ≤ nc.

A First-Principles Study of Electron-Phonon Coupling of OsB2

2014 ◽  
Vol 597 ◽  
pp. 113-116
Author(s):  
Yue Qin Wang ◽  
Juan Gao ◽  
Shao Ping Yan
Keyword(s):  
Transition Temperature ◽  
First Principles ◽  
Linear Response ◽  
Lattice Dynamics ◽  
Superhard Material ◽  
Superconducting Transition ◽  
Phonon Coupling ◽  
Phonon Modes ◽  
Electron Phonon Coupling ◽  
Coulomb Pseudopotential

We investigated the lattice dynamics and electron-phonon coupling (EPC) of superhard material OsB2by first-principles linear response calculations. The calculated EPC parameters for the optical phonon modes at Г indicate that the heavy Os atoms play the most important role in deciding the superconducting behavior, and there are sizeable contributions from lighter B atoms to EPC. Our calculated EPC constant is 0.42, and the estimated superconducting transition temperatureTcis 2.1 K using the Coulomb pseudopotentialμ*=0.125, in excellent agreement with the experimental ones.

Electron–phonon coupling constant and critical temperature of binary and ternary superconducting alloys of V, Nb, Mo, and Ta

1980 ◽  
Vol 58 (9) ◽  
pp. 1383-1387 ◽  
Author(s):  
Parsathi Chatterjee
Keyword(s):  
Superconducting Transition ◽  
Matrix Approximation ◽  
Body Centered Cubic ◽  
Coupling Constant ◽  
Phonon Coupling ◽  
Transition Elements ◽  
Electron Phonon Coupling ◽  
Exchange Approximation ◽  
Cubic Structure ◽  
Substitutional Alloys

A modified version of the theory of Gaspari and Gyorffy for calculating the electron–phonon coupling constant, λ, for binary substitutional alloys has been used in conjunction with McMillan's expression as modified by Dynes for the superconducting transition temperature, Tc, to obtain λ and Tc for the substitutional alloys NbTa, NbV, VMo, VTa, and TaMo. The theory has been further extended via the Average T-matrix Approximation to calculate λ and Tc for the ternary alloy, NbTaMo, having the same body-centered cubic structure as its components. The calculations of λ are based on self-consistent APW or KRR band structure data for the transition elements V, Nb, Mo, and Ta, obtained by using either Xα or the Hedin–Lundqvist version of the [Formula: see text] exchange approximation to calculate the potentials. The results thus obtained at different concentrations agree favourably with experiments for NbTa, NbV, VMo, and VTa. For TaMo and NbTaMo, for which experimental data on Tc are not yet available, we predict that they are fairly good superconductors.

AN EFFICIENT METHOD OF DETERMINING SUPERCONDUCTING TRANSITION TEMPERATURE Tc

2005 ◽  
Vol 19 (05) ◽  
pp. 221-224
Author(s):  
DEHUA LIN ◽  
CHAORONG ZHONG ◽  
ZHIFENG LI ◽  
BINGQUAN HU ◽  
XINGANG WU ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Influencing Factors ◽  
Efficient Method ◽  
Superconducting Transition Temperature ◽  
Simple Technique ◽  
Transition Temperatures ◽  
Superconducting Transition

In this paper, by using simple technique we introduce an efficient method of determining superconducting transition temperatures in experiment, we have also figured out the main influencing factors on the accuracy of Tc measurement. We present a useful relationship and the calculating formulae. This method is suited to determine superconducting transition temperatures in superconductors at temperatures of liquid He as well.

ELECTRON–PHONON PAIRING IN THE HUBBARD MODEL

1992 ◽  
Vol 06 (09) ◽  
pp. 541-546 ◽  
Author(s):  
N. M. PLAKIDA ◽  
V. S. UDOVENKO
Keyword(s):  
Transition Temperature ◽  
Hubbard Model ◽  
Function Technique ◽  
Superconducting Transition ◽  
Strong Correlations ◽  
Phonon Coupling ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Electron Phonon Coupling ◽  
The Green Function

A system of electrons with strong correlations is considered within the framework of a single-band Hubbard model with a strong anharmonic electron-phonon interaction. The dependence of superconducting transition temperature T c on carrier concentration n is obtained using the Green function technique. It is shown that, due to the nonlocal character of electron–phonon coupling in the model, T c (n) strongly depends on the symmetry of the gap.

TWO-COMPONENT ALLOY MODEL FOR BISMUTHATE CERAMICS

1996 ◽  
Vol 10 (14) ◽  
pp. 627-633
Author(s):  
A.L. KUZEMSKY
Keyword(s):  
Transition Temperature ◽  
Strong Coupling ◽  
Concentration Dependence ◽  
Coupling Constant ◽  
Phonon Coupling ◽  
Superconducting Properties ◽  
Disordered Alloys ◽  
Electron Phonon Coupling ◽  
Two Component

The disordered binary substitutional A 1−x B x alloy model has been proposed for the description of the normal and superconducting properties of bismuthate ceramics Ba(Pb,Bi)O 3. The Eliashberg-type equations for the strong coupling superconductivity in strongly disordered alloys have been used to describe the superconducting properties. The relevant configurational averaging has been performed in the framework of CPA. The concentration dependence of electron-phonon coupling constant λ(x) and transition temperature Tc(x) has been calculated.

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