INTERFACE AND STEP LOCALIZED PHONON MODES BETWEEN TWO TRUNCATED THIN FILMS

2004 ◽  
Vol 11 (02) ◽  
pp. 155-165
Author(s):  
M. TAMINE ◽  
H. BOUMRAR ◽  
O. RAFIL
Keyword(s):  
Thin Films ◽  
Strain Field ◽  
Phonon Dispersion ◽  
Harmonic Approximation ◽  
Elastic Force ◽  
Force Constants ◽  
Step Edge ◽  
Dimensional Structure ◽  
Phonon Modes ◽  
Low Dimensional

We have carried out the calculations of vibrational dynamics in the low-dimensional structure with dimensions on the nanometer scale by using the matching formalism. The nanostructure model consists in the surface step produced at a perpendicular interface between two truncated thin films with different thickness. The theoretical approach determines the vibrational field in the direction where the translation symmetry is broken. The calculation concerns in particular the phonon dispersion curves localized on the interface and step edge, and employs the matching procedure in the harmonic approximation. The nearest and next nearest neighbors elastic force constants between the mass sites in the model, as well as a modification of the elastic strain field induced by the presence of the step, are considered. Analytic expressions are obtained for the phonon dispersion relations of the localized surface and edge elastic waves and the bulk phonons near a step. The breakdown of translational symmetry perpendicular to the step edge gives rise to several Raleigh-like branches localized in the neighborhood of step and interface. The effects of varying the elastic force constants at an interface and the strain field parameter near the step are studied. These factors influence the number of localized modes as well as their frequency, intensity and attenuation.

NOVEL ROOM TEMPERATURE ELECTROCHEMICAL DEPOSITION OF HIGH TEMPERATURE SUPERCONDUCTING FILMS

2004 ◽  
Vol 18 (12n13) ◽  
pp. 505-549 ◽  
Author(s):  
S. H. PAWAR ◽  
P. M. SHIRAGE ◽  
D. D. SHIVAGAN ◽  
A. B. JADHAV
Keyword(s):  
Thin Films ◽  
Electrochemical Deposition ◽  
Room Temperature ◽  
Electrochemical Techniques ◽  
Deposition Process ◽  
Superconducting Films ◽  
Dimensional Structure ◽  
Hetero Structure ◽  
Review Reports ◽  
Low Dimensional

The present review reports the innovative attempts made in the synthesis of a variety of high T c superconductor families in the form of thin films by electrochemical techniques. Summarizing the brief background of electrochemical deposition process, the growth mechanism of high T c superconducting films has been explained. The successful stories of room temperature electrochemical deposition of RE - Ba 2 Cu 3 O 7-δ, Bi – Sr – Ca – CuO , Tl – Ba – Ca – CuO , Hg – Ba – Ca – CuO and MgB2 superconductors in the form of thin films on silver substrates have been summarized. The room temperature electrochemical synthesis technique has helped to form a low-dimensional structure at the interface of Al/Tl-2223 hetero structure, which leads to a pathway for high T c and J c . The photoinduced effects of a variety of heterostructures formed with HTSC systems and CdSe semiconductor are also described.

scholarly journals A First-Principle Study of Monolayer Transition Metal Carbon Trichalcogenides

2021 ◽  
Author(s):  
Muhammad Yar Khan ◽  
Yan Liu ◽  
Tao Wang ◽  
Hu Long ◽  
Miaogen Chen ◽  
...  
Keyword(s):  
Phonon Dispersion ◽  
Magnetic Ordering ◽  
Dimensional Structure ◽  
First Principle ◽  
Two Dimensional ◽  
Biaxial Strain ◽  
Half Metallic ◽  
First Principle Calculations ◽  
Potential Applications ◽  
External Strain

AbstractMonolayer MnCX3 metal–carbon trichalcogenides have been investigated by using the first-principle calculations. The compounds show half-metallic ferromagnetic characters. Our results reveal that their electronic and magnetic properties can be altered by applying uniaxial or biaxial strain. By tuning the strength of the external strain, the electronic bandgap and magnetic ordering of the compounds change and result in a phase transition from the half-metallic to the semiconducting phase. Furthermore, the vibrational and thermodynamic stability of the two-dimensional structure has been verified by calculating the phonon dispersion and molecular dynamics. Our study paves guidance for the potential applications of these two mono-layers in the future for spintronics and straintronics devices.

Phonon renormalization of the electronic effective mass

1969 ◽  
Vol 47 (10) ◽  
pp. 1107-1116 ◽  
Author(s):  
J. P. Carbotte ◽  
R. C. Dynes ◽  
P. N. Trofimenkoff
Keyword(s):  
Effective Mass ◽  
Phonon Dispersion ◽  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Force Constants ◽  
Coupling Constant ◽  
Phonon Dispersion Curves ◽  
Electron Phonon Interaction ◽  
Phonon Renormalization ◽  
Pseudo Potential

We have made detailed first principle calculations of the phonon contribution to the renormalization of the electronic effective mass of a number of simple metals and alloys. The phonon frequencies and polarization vectors are generated from the interatomic force constants for the material. The force constants are taken from a Born – von Kármán analysis of the experimental phonon dispersion curves determined by inelastic neutron scattering. The electron–phonon interaction is treated using pseudo-potential theory which relates the coupling constant to the electron–ion form factor. For a spherical Fermi surface it is then possible to evaluate numerically the expression for the effective mass with no further approximations. We compare the results obtained with previous work when available and with experiment otherwise.

Chemical Bath Deposition of Lead Sulphide (PbS) Thin Film and their Characterization

2013 ◽  
Vol 209 ◽  
pp. 111-115 ◽  
Author(s):  
Sandip V. Bhatt ◽  
M.P. Deshpande ◽  
Bindiya H. Soni ◽  
Nitya Garg ◽  
Sunil H. Chaki
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Raman Spectroscopy ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Excitation Wavelength ◽  
Face Centered Cubic ◽  
Phonon Modes ◽  
Lead Sulphide ◽  
X Ray

Thin film deposition of PbS is conveniently carried out by chemical reactions of lead acetate with thiourea at room temperature. Energy dispersive analysis of X-ray (EDAX), X-ray diffraction (XRD), selected area electron diffraction patterns (SAED), UV-Vis-NIR spectrophotometer, Scanning Electron Microscopy (SEM), Atomic force microscopy (AFM), Photoluminescence (PL) and Raman spectroscopy techniques are used for characterizing thin films. EDAX spectra shows that no impurity is present and XRD pattern indicates face centered cubic structure of PbS thin films. The average crystallite size obtained using XRD is about 15nm calculated using Scherrer’s formula and that determined from Hall-Williamson plot was found to be 18nm. SAED patterns indicate that the deposited PbS thin films are polycrystalline in nature. Blue shift due to quantum confinement was seen from the UV-Vis-NIR absorption spectra of thin film in comparison with bulk PbS. The Photoluminescence spectra obtained for thin film with different excitation sources shows sharp emission peaks at 395nm and its intensity of photoluminescence increases with increasing the excitation wavelength. Raman spectroscopy of deposited thin film was used to study the optical phonon modes at an excitation wavelength of 488nm using (Ar+) laser beam.

Ordered growth of germanium dots induced by the strain field of tilt dislocations in molecular bonded silicon (001) thin films

2006 ◽  
Vol 600 (11) ◽  
pp. L135-L138 ◽  
Author(s):  
V. Poydenot ◽  
R. Dujardin ◽  
J.L. Rouvière ◽  
A. Barski ◽  
J. Mezière ◽  
...  
Keyword(s):  
Thin Films ◽  
Strain Field

Step-Edge Josephson Junctions using Tl2Ba2CaCu2Ox Thin Films on MgO Substrates

1996 ◽  
pp. 1105-1108 ◽  
Author(s):  
Shuichi Yoshikawa ◽  
Masaaki Nemoto ◽  
Ryokan Yuasa ◽  
Kazuhiro Shimaoka ◽  
Kazuya Niki ◽  
...  
Keyword(s):  
Thin Films ◽  
Josephson Junctions ◽  
Step Edge
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