Scattering and Tunneling of Electronic Excitations in the Intermediate State of Superconductors

1971 ◽  
Vol 49 (3) ◽  
pp. 285-295 ◽  
Author(s):  
Jacques Demers ◽  
Allan Griffin
Keyword(s):  
Thermal Resistance ◽  
Intermediate State ◽  
Bound States ◽  
Normal Metal ◽  
Anomalous Scattering ◽  
Electronic Excitations ◽  
Superconducting Layer ◽  
Quasi Particle ◽  
Transmission Resonances ◽  
Bogoliubov Excitations

We give a systematic discussion of the anomalous scattering of Bogoliubov excitations at sharp N–S and S–N boundaries as well as quasi-particle tunneling in N–S–N and S–N–S geometries. The relation between the transmission resonances (E > Δ) and the bound states (E < Δ) in N–S–N and S–N–S geometries is explicitly exhibited. We also work out the extra thermal resistance due to scattering by a normal layer imbedded in a superconductor and by a superconducting layer imbedded in a normal metal, with results different from that obtained by Shikin.

scholarly journals Proximity effect in a two-dimensional electron gas coupled to a thin superconducting layer

2018 ◽  
Vol 9 ◽  
pp. 1263-1271 ◽  
Author(s):  
Christopher Reeg ◽  
Daniel Loss ◽  
Jelena Klinovaja
Keyword(s):  
Bound States ◽  
Topological Phase ◽  
Two Dimensional ◽  
Dimensional Electron ◽  
Electron Gases ◽  
Band Shift ◽  
Superconducting Layer ◽  
Strongly Coupled ◽  
Semiconducting Material ◽  
Dimensional Electron Gas

There have recently been several experiments studying induced superconductivity in semiconducting two-dimensional electron gases that are strongly coupled to thin superconducting layers, as well as probing possible topological phases supporting Majorana bound states in such setups. We show that a large band shift is induced in the semiconductor by the superconductor in this geometry, thus making it challenging to realize a topological phase. Additionally, we show that while increasing the thickness of the superconducting layer reduces the magnitude of the band shift, it also leads to a more significant renormalization of the semiconducting material parameters and does not reduce the challenge of tuning into a topological phase.

Picosecond Studies of Nonequilibrium Flux Dynamics in Superconductors

1992 ◽  
Vol 290 ◽  
Author(s):  
M. R. Freeman
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Intermediate State ◽  
Nonequilibrium State ◽  
Normal Metal ◽  
Fast Time ◽  
Type I ◽  
Superconducting Transition ◽  
Local Motion ◽  
Flux Dynamics

AbstractA fast time-domain magneto-optical technique is used to explore magnetic flux dynamics in the optically driven nonequilibrium state of Type I superconducting Pb films. It is found that the effective penetration of flux through the nonequilibrium intermediate state can be dramatically faster than through the normal metal. The system is probed through the application of rapid transient magnetic field pulses. Above the superconducting transition temperature, a direct measure of the diffusion coefficient of the magnetic field in the normal metal is obtained, on a time scale where the inhomogeneous spatial distribution of scattering sites is relevant. In the nonequilibrium superconductor the observations are dominated by coupling of the field transients to local motion of magnetic flux threading the normal domains. Studies as a function of how far the system is driven from equilibrium, and of the effect of a static applied magnetic field, indicate that the observations reflect the dynamics of normal/superconducting interfaces, and are strongly dependent on the microscopic arrangement of the intermediate state. By contrasting the response of pure Pb films to that of Pb1−xInx alloys, a comparison to Type II superconductivity is made.

scholarly journals Kondo screening of Andreev bound states in a normal metal–quantum dot–superconductor system

2016 ◽  
Vol 94 (16) ◽  
Author(s):  
Lin Li ◽  
Zhan Cao ◽  
Tie-Feng Fang ◽  
Hong-Gang Luo ◽  
Wei-Qiang Chen
Keyword(s):  
Quantum Dot ◽  
Bound States ◽  
Normal Metal ◽  
Andreev Bound States ◽  
Kondo Screening

scholarly journals Dirac Particle for the Position Dependent Mass in the Generalized Asymmetric Woods-Saxon Potential

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Soner Alpdoğan ◽  
Ali Havare
Keyword(s):  
Bound States ◽  
Dirac Particle ◽  
Saxon Potential ◽  
One Dimensional ◽  
Transmission And Reflection Coefficients ◽  
Scattering States ◽  
Transmission Resonances ◽  
The One ◽  
Dependent Mass ◽  
Position Dependent Mass

The one-dimensional Dirac equation with position dependent mass in the generalized asymmetric Woods-Saxon potential is solved in terms of the hypergeometric functions. The transmission and reflection coefficients are obtained by considering the one-dimensional electric current density for the Dirac particle and the equation describing the bound states is found by utilizing the continuity conditions of the obtained wave function. Also, by using the generalized asymmetric Woods-Saxon potential solutions, the scattering states are found out without making calculation for the Woods-Saxon, Hulthen, cusp potentials, and so forth, which are derived from the generalized asymmetric Woods-Saxon potential and the conditions describing transmission resonances and supercriticality are achieved. At the same time, the data obtained in this work are compared with the results achieved in earlier studies and are observed to be consistent.

scholarly journals FRACTIONALLY CHARGED EXCITATIONS ON FRUSTRATED LATTICES

2007 ◽  
Vol 21 (13n14) ◽  
pp. 2215-2231 ◽  
Author(s):  
E. RUNGE ◽  
F. POLLMANN ◽  
P. FULDE
Keyword(s):  
Bound States ◽  
Additional Parameter ◽  
Strongly Correlated ◽  
Spectral Functions ◽  
Quasi Particle ◽  
Geometrically Frustrated ◽  
Quantum Numbers ◽  
Finite Lattices ◽  
Strongly Correlated Fermions ◽  
Fine Tune

Systems of strongly correlated fermions on certain geometrically frustrated lattices at particular filling factors support excitations with fractional charges ±e/2. We calculate quantum mechanical ground states, low–lying excitations and spectral functions of finite lattices by means of numerical diagonalization. The ground state of the most thorough-fully studied case, the criss-crossed checkerboard lattice, is degenerate and shows long–range order. Static fractional charges are confined by a weak linear force, most probably leading to bound states of large spatial extent. Consequently, the quasi-particle weight is reduced, which reflects the internal dynamics of the fractionally charged excitations. By using an additional parameter, we fine–tune the system to a special point at which fractional charges are manifestly deconfined—the so–called Rokhsar–Kivelson point. For a deeper understanding of the low–energy physics of these models and for numerical advantages, several conserved quantum numbers are identified.

Electronic excitations of stable fullerene-like GaP clusters

2004 ◽  
Vol 854 ◽  
Author(s):  
Giuliano Malloci ◽  
Giancarlo Cappellini ◽  
Giacomo Mulas ◽  
Guido Satta
Keyword(s):  
Optical Absorption ◽  
Absorption Spectra ◽  
Density Functional ◽  
Electronic Excitations ◽  
Optical Absorption Spectra ◽  
Functional Theory ◽  
Quasi Particle ◽  
New Class ◽  
Excitonic Effects ◽  
Homo Lumo

ABSTRACTWe present quasi-particle (QP) corrections to the electronic energies for small GaP fullerenes, a new class of nanoscaled materials predicted to be stable and to show spontaneous formation. Using Time-Dependent Density Functional Theory we also computed the optical absorption spectra. The comparison between single-particle and optical absorption spectra yields strong excitonic effects with bonding energy up to 3.5 eV. The QP corrected HOMO-LUMO energy gaps confirm the high stability predicted for such molecules using ground-state computational schemes. The present results can be useful to identify the successful synthesis of these systems via optical absorption and QP spectra.

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