scholarly journals Creating better superconductors by periodic nanopatterning

2017 ◽  
Vol 3 (2) ◽  
Author(s):  
Milan Allan ◽  
Mark H Fischer ◽  
Oliver Ostojic ◽  
Arjo Andringa
Keyword(s):  
Thin Films ◽  
Transition Temperature ◽  
Numerical Methods ◽  
Model Calculation ◽  
Lattice Mismatch ◽  
Specific Pattern ◽  
Design Parameters ◽  
Phonon Coupling ◽  
Electron Phonon Coupling ◽  
Correct Design

The quest to create superconductors with higher transition temperatures is as old as superconductivity itself. One strategy, popular after the realization that (conventional) superconductivity is mediated by phonons, is to chemically combine different elements within the crystalline unit cell to maximize the electron-phonon coupling. This led to the discovery of NbTi and Nb_33Sn, to name just the most technologically relevant examples. Here, we propose a radically different approach to transform a ‘pristine’ material into a better (meta-) superconductor by making use of modern fabrication techniques: designing and engineering the electronic properties of thin films via periodic patterning on the nanoscale. We present a model calculation to explore the key effects of different supercells that could be fabricated using nanofabrication or deliberate lattice mismatch, and demonstrate that specific pattern will enhance the coupling and the transition temperature. We also discuss how numerical methods could predict the correct design parameters to improve superconductivity in materials including Al, NbTi, and MgB_22.

scholarly journals Raman study of electron-phonon coupling in thin films of the spinel oxide superconductor LiTi2O4

2017 ◽  
Vol 96 (9) ◽  
Author(s):  
D. Chen ◽  
Y.-L. Jia ◽  
T.-T. Zhang ◽  
Z. Fang ◽  
K. Jin ◽  
...  
Keyword(s):  
Thin Films ◽  
Oxide Superconductor ◽  
Phonon Coupling ◽  
Spinel Oxide ◽  
Electron Phonon Coupling ◽  
Raman Study

Model calculation of the electron-phonon coupling in Cs/Cu(111)

2008 ◽  
Vol 78 (3) ◽  
Author(s):  
Akihiro Nojima ◽  
Koichi Yamashita ◽  
Bo Hellsing
Keyword(s):  
Model Calculation ◽  
Phonon Coupling ◽  
Electron Phonon Coupling

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.

Influence of disorder strength on the superconducting mechanism of MgB2

2021 ◽  
Author(s):  
Jung Min Lee ◽  
Soon-Gil Jung ◽  
Younseok Han ◽  
Tae-Ho Park ◽  
Jae Kyung Jang ◽  
...  
Keyword(s):  
Thin Films ◽  
Ion Irradiation ◽  
Electronic System ◽  
Coupling Constants ◽  
Disorder Strength ◽  
Coupling Constant ◽  
Phonon Coupling ◽  
Normal State Resistivity ◽  
Electron Phonon Coupling ◽  
Effect Of Disorder

Abstract We investigate the effect of disorder on the superconducting mechanism of MgB2 thin films using low-energy ion irradiation. The c-axis lattice constant and T c of MgB2 thin films change systematically as the magnitude of disorder, which corresponds to the value of average displacements per atom (dpaavg ), increases. Here, dpaavg is controlled by the amount of irradiated ions. The dpaavg dependence of the electron-phonon coupling constants (λ) is estimated using the McMillan equation. For dpaavg ≤ 0.049, λ is linearly proportional to dpaavg . On the other hand, for dpaavg > 0.049, the T c of the disordered MgB2 deviates from the linear fitting curve, and insulating behavior is observed in the normal state resistivity. These results indicate that the superconducting mechanism of MgB2 can be changed by the electronic system caused by disorder strength affecting the electron-phonon coupling constant λ.

scholarly journals Probing the electron-phonon coupling in MgB 2 through magnetoresistance measurements in neutron irradiated thin films

2008 ◽  
Vol 81 (6) ◽  
pp. 67006 ◽  
Author(s):  
M. Monni ◽  
I. Pallecchi ◽  
C. Ferdeghini ◽  
V. Ferrando ◽  
A. Floris ◽  
...  
Keyword(s):  
Thin Films ◽  
Phonon Coupling ◽  
Electron Phonon Coupling

Volume dependence of superconducting state parameters of bismuth-based binary alloys: A pseudopotential approach

2019 ◽  
Vol 33 (32) ◽  
pp. 1950394
Author(s):  
Hiral Patel ◽  
Priyank Kumar ◽  
N. K. Bhatt ◽  
P. R. Vyas ◽  
V. B. Gohel
Keyword(s):  
Transition Temperature ◽  
Effective Interaction ◽  
Interaction Strength ◽  
Grüneisen Parameter ◽  
Phonon Coupling ◽  
Gruneisen Parameter ◽  
Volume Dependence ◽  
Electron Phonon Coupling ◽  
Strength Formula ◽  
Coulomb Pseudopotential

A comprehensive and systematic study of superconducting state parameters (SSPs) of Bi-based binary alloys of the form [Formula: see text] has been carried out in the framework of pseudopotential theory at different concentrations ([Formula: see text]) of impurity atom-[Formula: see text] in host atom Bi which varies from 0 to 1. Impurity atom [Formula: see text] has been replaced by In, Tl, Sb and Pb to form four alloy systems. The density-based local form of the pseudopotential proposed by Fiolhais et al. has been used in this study to compute SSPs such as electron–phonon coupling strength ([Formula: see text]), Coulomb pseudopotential ([Formula: see text]), transition temperature ([Formula: see text]), effective interaction strength ([Formula: see text] and isotopic effect parameter ([Formula: see text]) of Bi-based binary alloy systems. Computed results of SSPs of alloys under study are in good agreement with available experimental and other theoretical results. In order to investigate the effect of pressure on SSPs of alloys under study, a theoretical calculation of SSPs as a function of compressed volume is reported. The volume dependence of Debye temperature has been accounted by using Debye–Gruneisen model which involves the Gruneisen parameter. Thus, to describe the effect of pressure on SSPs accurately, the value of Gruneisen parameter should be as accurate as possible. But reported results of Gruneisen parameter in the literature are highly scattered. Due to this reason, we have used two sets of Gruneisen parameter obtained by different methods to understand its role in the computation of SSPs as a function of compressed volume. Further, critical volumes for all alloys at different concentration have been predicted at which electron–phonon coupling strength and Coulomb pseudopotential are equal ([Formula: see text]). At critical volume, superconductivity quenches where transition temperature, [Formula: see text], and effective interaction strength, [Formula: see text], become zero. It is observed that critical volumes predicted by all approaches used in this study are in excellent agreement with each other.

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