Transverse phonon scattering in s-wave superconductors: the role of BCS coherence factors and Meissner screening near Tc

2002 ◽  
Vol 15 (8) ◽  
pp. 1252-1258 ◽  
Author(s):  
K Fossheim ◽  
N T Opheim ◽  
H Bratsberg
Keyword(s):  
Phonon Scattering ◽  
S Wave ◽  
Transverse Phonon ◽  
Coherence Factors

Lattice Thermal Conductivity Modelling of a Diatomic Nanoscale Material

2020 ◽  
Vol 10 (5) ◽  
pp. 602-609
Author(s):  
Adil H. Awad
Keyword(s):  
Thermal Conductivity ◽  
Lattice Thermal Conductivity ◽  
Phonon Scattering ◽  
Correction Term ◽  
Nanoscale Material ◽  
New Approach ◽  
Two Samples ◽  
Conductivity Modelling ◽  
Callaway Model

Introduction: A new approach for expressing the lattice thermal conductivity of diatomic nanoscale materials is developed. Methods: The lattice thermal conductivity of two samples of GaAs nanobeam at 4-100K is calculated on the basis of monatomic dispersion relation. Phonons are scattered by nanobeam boundaries, point defects and other phonons via normal and Umklapp processes. Methods: A comparative study of the results of the present analysis and those obtained using Callaway formula is performed. We clearly demonstrate the importance of the utilised scattering mechanisms in lattice thermal conductivity by addressing the separate role of the phonon scattering relaxation rate. The formulas derived from the correction term are also presented, and their difference from Callaway model is evident. Furthermore their percentage contribution is sufficiently small to be neglected in calculating lattice thermal conductivity. Conclusion: Our model is successfully used to correlate the predicted lattice thermal conductivity with that of the experimental observation.

scholarly journals A MICROSCOPIC CLUSTER MODEL STUDY OF 3He + p SCATTERINGS

2010 ◽  
Vol 25 (21n23) ◽  
pp. 1750-1753
Author(s):  
K. ARAI ◽  
S. AOYAMA ◽  
Y. SUZUKI
Keyword(s):  
Cluster Model ◽  
Nucleon Nucleon ◽  
Phase Shifts ◽  
Minor Role ◽  
S Wave ◽  
P Waves ◽  
Model Study ◽  
Three Body ◽  
A Minor

3 He + p scattering phase shifts for the S- and P-waves are studied in a microscopic cluster model in order to investigate the role of the d + 2p channel in the low-energy phase shifts. In the present cluster model, the description of the 3 He wave function is extended from a simple (0s)3 model to a three-body model and two different nucleon-nucleon interactions, the Minnesota and AV8' potentials, are employed. The present extended cluster model shows that the d + 2p channel is indispensable to reproduce the resonant phase shifts in the AV8' potential while it plays a minor role in the MN potential. On the contrary, the role of this channel in the S-wave non-resonant phase shifts is negligible in both potentials.

scholarly journals Energy-filtered electron diffuse scattering of ferroelectrics PMN and PMN-xPT

2014 ◽  
Vol 70 (a1) ◽  
pp. C623-C623
Author(s):  
Jerome Pacaud ◽  
Wajdi Saidi ◽  
Ray Withers ◽  
Brahim Dkhil ◽  
Jian-Min Zuo
Keyword(s):  
Diffuse Scattering ◽  
Phonon Scattering ◽  
Relaxor Ferroelectrics ◽  
Charge Ordering ◽  
Diffuse Intensity ◽  
Sufficient Energy ◽  
Direct Lattice ◽  
Imaging Plates ◽  
Dielectric And Piezoelectric Properties

PbMb1/3Nb2/3O3 (PMN) and its solid solution (1-x)PbMb1/3Nb2/3O3-(x)PbTiO3 (PMN-xPT) are relaxor ferroelectrics which have attracted attention in the last few decades because of their very interesting dielectric and piezoelectric properties and have since be two of the most extensively studied. All the previous studies emphasized the role of the local structural fluctuations leading to local changes in symmetries [1] due to displacements of ions in the unit-cell. We studied PMN and PMN-xPT by electron diffuse scattering using an in-column energy filter and Imaging-Plates as detector. We found evidences for streaks of intensity along the [110]* direction as previously found in PbZn1/3Nb2/3O3 (PZN) with neutron diffraction [2]. Moreover, weak diffuse scattering sheets can be observed along (111)* reciprocal planes showing the existence of correlations along the [111] directions of the direct lattice. Figure 1 shows a diffraction pattern taken along [02-1] zone axis presenting both diffuse features. This can be related to the displacement of Pb ions along the diagonals of the cube found by simulation [3] but greatly complexify the analysis of the shape of the diffuse intensity. Compared to the neutron, electron diffraction has the advantage of two dimensional recording of diffuse scattering and eventually sensitivity to charge ordering but quantitative analysis is limited due to the complication of multiple scattering and the lack of sufficient energy resolution for the study of inelastic phonon scattering.

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