scholarly journals Inelastic electron-phonon scattering and excess current in superconducting point contacts with a short coherence length

2015 ◽  
Vol 41 (8) ◽  
pp. 595-601 ◽  
Author(s):  
N. L. Bobrov
Keyword(s):  
Coherence Length ◽  
Phonon Scattering ◽  
Inelastic Electron ◽  
Point Contacts ◽  
Excess Current ◽  
Electron Phonon Scattering

Coupled Non-Equilibrium Green’s Function (NEGF) Electron-Phonon Interaction in Thermoelectric Materials

2011 ◽  
Author(s):  
T. D. Musho ◽  
D. G. Walker
Keyword(s):  
Thermoelectric Materials ◽  
Thermal Transport ◽  
Phonon Scattering ◽  
Computational Method ◽  
Direct Result ◽  
Inelastic Electron ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Electron Phonon Scattering ◽  
Non Equilibrium

Over the last decade, nano-structured materials have shown a promising avenue for enhancement of the thermoelectric figure of merit. These performance enhancements in most cases have been a direct result of selectively modifying certain geometric attributes that alter the thermal or electrical transport in a desirable fashion. More often, models used to study the electrical and/or thermal transport are calculated independent of each other. However, studies have suggested electrical and thermal transport are intimately linked at the nanoscale. This provides an argument for a more rigorous treatment of the physics in an effort to capture the response of both electrons and phonons simultaneously. A simulation method has been formulated to capture the electron-phonon interaction of nanoscale electronics through a coupled non-equilibrium Greens function (NEGF) method. This approach is unique because the NEGF electron solution and NEGF phonon solution have only been solved independently and have never been coupled to capture a self-consistent inelastic electron-phonon scattering. One key aspect of this formalism is that the electron and phonon description is derived from a quantum point of view and no correction terms are necessary to account for the probabilistic nature of the transport. Additionally, because the complete phonon description is solved, scattering rates of individual phonon frequencies can be investigated to determine how electron-phonon scattering of particular frequencies influences the transport. This computational method is applied to the study of Si/Ge nanostructured superlattice thermoelectric materials.

Normal metal point contacts

1982 ◽  
Vol 60 (5) ◽  
pp. 740-745 ◽  
Author(s):  
H. van Kempen
Keyword(s):  
Electron Scattering ◽  
Kondo Effect ◽  
Phonon Scattering ◽  
Point Contact ◽  
High Current ◽  
Point Contacts ◽  
Paramagnetic Impurities ◽  
Normal Metals ◽  
Current Densities ◽  
Electron Phonon Scattering

Under conditions of extremely high current densities, deviations from the linear current (I) – voltage (V) relation (Ohm's law) occur in normal metals. One can obtain sufficiently high current densities (of the order of 1010 A/cm2) by applying a voltage to a point contact. The nonlinear Boltzmann equation relates the nonlinearities to the energy dependence of the electron scattering probabilities. It is shown, for example, that d2V/dI2 is proportional to α2(ω)F(ω), where F(ω) is the phonon density of states and α(ω) is the electron–phonon scattering matrix element. In addition other interactions arc studied by this method such as electron–magnon interaction and the interaction of electrons with paramagnetic impurities, the well-known Kondo effect. A double point contact geometry is described which allows electron–surface scattering to be studied.

INVESTIGATION OF STRUCTURE AND ELECTRICAL TRANSPORT IN PARTIALLY NANOCRYSTALLIZED AMORPHOUS SOFT MAGNETIC ALLOYS

2002 ◽  
Vol 16 (26) ◽  
pp. 4003-4016
Author(s):  
K. BALAKRISHNAN ◽  
Y. SUNDARAYYA ◽  
M. K. NAIDU ◽  
S. N. KAUL
Keyword(s):  
Electrical Transport ◽  
Quantum Interference ◽  
Phonon Scattering ◽  
Spin Fluctuation ◽  
Diffusion Constant ◽  
Electron Interaction ◽  
Inelastic Electron ◽  
Constant Density ◽  
Breaking Time ◽  
Electron Phonon Scattering

X-ray diffraction patterns of melt-spun Fe-Cu-Nb-Si-B (FINEMET-type) alloys reveal that crystallites of Fe 2 Si and Fe 3 B phases with average sizes of 15(5) and 20(2) nm are present in the surface layer of thickness ≈ 10 Å and these nanocrystallites occupy 5–10% of the total volume. The results of an elaborate analysis of the high-resolution electrical resistivity data taken in a temperature range from 13 K to 300 K and their discussion in the light of existing theories demonstrates that the enhanced electron–electron interaction (EEI), quantum interference (QI) effects, inelastic electron–phonon scattering, coherent electron–magnon (and/or electron-spin fluctuation) scattering are the main mechanisms that govern the temperature dependence of resistivity. Of all the inelastic scattering processes, inelastic electron–phonon scattering is the most effective mechanism to destroy phase coherence of electron wavefunctions. The physical quantities such as diffusion constant, density of states at the Fermi level and the phase-breaking time, determined for the first time for the alloys in question, exhibit a systematic variation with the copper concentration.

Role of Inelastic Electron-Phonon Scattering in Ultra-Scaled Phase Change Material Nanostructures

2014 ◽  
Vol 1697 ◽  
Author(s):  
Jie Liu ◽  
Xu Xu ◽  
M. P. Anantram
Keyword(s):  
Electron Transport ◽  
Phase Change ◽  
Phase Change Material ◽  
Phonon Scattering ◽  
Channel Length ◽  
Inelastic Electron ◽  
Atomic Lattice ◽  
Current Voltage Curve ◽  
Change Material ◽  
Electron Phonon Scattering

ABSTRACTThe electron transport properties of ultra-scaled amorphous phase change material (PCM) GeTe are studied using non-equilibrium Green’s function (NEGF). The inelastic electron-phonon scattering is included using Born approximation. It is shown that, in ultra-scaled PCM device with 6 nm channel length, less than 4% of the energy carried by the incident electrons from the source is transferred to the atomic lattice before reaching the drain, indicating that the electron transport is largely elastic. Our simulation results show that the inelastic electron-phonon scattering, which plays an important role to excite trapped electrons in bulk PCM devices, exerts very limited influence on the current density value and the shape of current-voltage curve of ultra-scaled PCM devices. The analysis reveals that the Poole-Frenkel law and the Ohm’s law, which are the governing physical mechanisms of the bulk PCM devices, cease to be valid in the ultra-scaled PCM devices.

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