Temperature-dependent dielectric loss in BaTiO3: Competition between tunnelling probability and electron-phonon interaction

2021 ◽  
Vol 257 ◽  
pp. 123792
Author(s):  
Aanchal Sati ◽  
Anil Kumar ◽  
Vikash Mishra ◽  
Kamal Warshi ◽  
Preeti Pokhriyal ◽  
...  
Keyword(s):  
Dielectric Loss ◽  
Temperature Dependent ◽  
Phonon Interaction ◽  
Electron Phonon Interaction

scholarly journals Temperature Dependence of G and D’ Phonons in Monolayer to Few-Layer Graphene with Vacancies

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Mingming Yang ◽  
Longlong Wang ◽  
Xiaofen Qiao ◽  
Yi Liu ◽  
Yufan Liu ◽  
...  
Keyword(s):  
Negative Temperature Coefficient ◽  
Negative Temperature ◽  
Intrinsic Properties ◽  
Temperature Dependent ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Layer Graphene ◽  
A Value ◽  
Few Layer Graphene

Abstract The defects into the hexagonal network of a sp2-hybridized carbon atom have been demonstrated to have a significant influence on intrinsic properties of graphene systems. In this paper, we presented a study of temperature-dependent Raman spectra of G peak and D’ band at low temperatures from 78 to 318 K in defective monolayer to few-layer graphene induced by ion C+ bombardment under the determination of vacancy uniformity. Defects lead to the increase of the negative temperature coefficient of G peak, with a value almost identical to that of D’ band. However, the variation of frequency and linewidth of G peak with layer number is contrary to D’ band. It derives from the related electron-phonon interaction in G and D’ phonon in the disorder-induced Raman scattering process. Our results are helpful to understand the mechanism of temperature-dependent phonons in graphene-based materials and provide valuable information on thermal properties of defects for the application of graphene-based devices.

Phonon Bottleneck Effect in Organic Molecules

2009 ◽  
Vol 1172 ◽  
Author(s):  
S. Bandyopadhyay ◽  
Bhargava Kanchibotla
Keyword(s):  
Spin Relaxation ◽  
Organic Molecules ◽  
Transverse Spin ◽  
Phonon Modes ◽  
Temperature Dependent ◽  
Phonon Interaction ◽  
Bottleneck Effect ◽  
Electron Phonon Interaction ◽  
Phonon Bottleneck ◽  
Dimension 2

AbstractWe have measured the ensemble averaged transverse spin relaxation time T2* (associated with g = 4 resonance) in bulk powders of the organic molecule Alq3, and in samples containing 1-2 molecules confined in nanocavities of dimension ˜ 2 nm. Both T2* times are strongly temperature dependent indicating that they are determined by phonon-mediated spin relaxation. Interestingly, the T2* time in nanocavities is ˜2.5 times longer than in bulk powder over a wide temperature range. The longer T2* in the nanocavity is evidence of weakened electron-phonon interaction. We believe that electron-phonon interaction is suppressed because the cavity confines phonons and discretizes the phonon modes and phonon energies. As a result, the chances of a phonon induced (inelastic) spin relaxation event are reduced owing to the need to conserve energy in the relaxation process. This is a novel “phonon bottleneck effect” that to our knowledge has not been previously reported.

scholarly journals Quantifying the Charge Carrier Interaction in Metallic Twisted Bilayer Graphene Superlattices

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1306
Author(s):  
Evgueni F. Talantsev
Keyword(s):  
Charge Carrier ◽  
Bilayer Graphene ◽  
Electron Interaction ◽  
Temperature Dependent ◽  
Phonon Interaction ◽  
Linear Temperature ◽  
Electron Phonon Interaction ◽  
Wide Range ◽  
Carrier Interaction ◽  
Twisted Bilayer Graphene

The mechanism of charge carrier interaction in twisted bilayer graphene (TBG) remains an unresolved problem, where some researchers proposed the dominance of the electron–phonon interaction, while the others showed evidence for electron–electron or electron–magnon interactions. Here we propose to resolve this problem by generalizing the Bloch–Grüneisen equation and using it for the analysis of the temperature dependent resistivity in TBG. It is a well-established theoretical result that the Bloch–Grüneisen equation power-law exponent, p, exhibits exact integer values for certain mechanisms. For instance, p = 5 implies the electron–phonon interaction, p = 3 is associated with the electron–magnon interaction and p = 2 applies to the electron–electron interaction. Here we interpret the linear temperature-dependent resistance, widely observed in TBG, as p→1, which implies the quasielastic charge interaction with acoustic phonons. Thus, we fitted TBG resistance curves to the Bloch–Grüneisen equation, where we propose that p is a free-fitting parameter. We found that TBGs have a smoothly varied p-value (ranging from 1.4 to 4.4) depending on the Moiré superlattice constant, λ, or the charge carrier concentration, n. This implies that different mechanisms of the charge carrier interaction in TBG superlattices smoothly transition from one mechanism to another depending on, at least, λ and n. The proposed generalized Bloch–Grüneisen equation is applicable to a wide range of disciplines, including superconductivity and geology.

On a current mechanism in Ta2O5 thin films

Open Physics ◽  
2008 ◽  
Vol 6 (4) ◽  
Author(s):  
Povilas Pipinys ◽  
Alfonsas Rimeika
Keyword(s):  
Tantalum Oxide ◽  
Interface Layer ◽  
Interaction Constant ◽  
Temperature Dependent ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Current Voltage ◽  
Crystal Substrate ◽  
A Current ◽  
Current Mechanism

AbstractElectrical conduction in the temperature range of 120–370 K has been studied in sandwiched structures of Al/Ta2O5/Si. The tantalum oxide films were prepared by evaporation of tantalum on a p-Si crystal substrate, followed by oxidation at a temperature of 600°C. The temperature-dependent current-voltage (I–V) characteristics are explained on the basis of a phonon-assisted tunnelling model. The same explanation is given for I–V data measured on Ta2O5 films by other investigators. From the comparison of experimental data with theory the density of states in the interface layer is derived and the electron-phonon interaction constant is assessed.

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