Home  About us  Contact
 

Scattering Potential (scattering + potential)

Distribution by Scientific Domains
Physics and Astronomy75%

Selected Abstracts

Isotope and disorder effects in the Raman spectra of LiHxD1,x crystals

JOURNAL OF RAMAN SPECTROSCOPY, Issue 8 2001
V. G. Plekhanov
Most of the physical properties of a solid depend on its isotopic composition in some way or another. Scientific interest, technological promise and increased availability of highly enriched isotopes have led to a sharp rise in the number of experimental and theoretical studies with isotopically controlled crystals. A great number of stable isotopes and well-developed methods for their separation have made it possible to grow crystals of C, LiH, ZnO, ZnSe, CuCl, GaN, GaAs, CdS, Cu2O, Si, Ge and ,-Sn with a controllable isotopic composition. Among these compounds, LiH possesses the largest value of the isotope effect. The great number of theoretical and experimental data suggest that the isotopic composition of a crystal lattice exerts some influence on the vibrational properties of crystals. These effects are fairly large and can be readily measured by modern experimental techniques (ultrasound, Brillouin and Raman scattering and neutron scattering). In addition, crystals of different isotopic compositions possess different Debye temperatures. This difference between an LiH crystal and its deuterated analogue exceeds a 100 K. Very pronounced and general effects of isotopic substitution are observed in phonon spectra. The scattering lines in isotopically mixed crystals are not only shifted (the shift of LO lines exceeds 100 cm,1) but are also broadened. This broadening is related to the isotopic disorder of the crystal lattice. It is shown that the degree of a change in the scattering potential is different for different isotopic mixed crystals. In the case of germanium and diamond crystals, phonon scattering is weak, which allows one to apply successfully the coherent potential approximation (CPA) for describing the shift and broadening of scattering lines. In the case of lithium hydride, the change in the scattering potential is so strong that it results in phonon localization, which is directly observed in experiments. The common nature of the isotopic and disorder effects in a wide range of crystals is emphasized. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Friedel oscillations in the presence of far from equilibrium heat transport

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 5 2009
A. Gorczyca
Abstract We investigate an inhomogeneous one-dimensional nanosystem coupled to macroscopic leads of different temperatures. In particular, we consider a system with an impurity with on-site scattering potential located in the middle of the nanowire. Such an impurity produces oscillations of the density of carriers in its vicinity, the so-called Friedel oscillations. In the equilibrium case these oscillations are symmetric with respect to the position of the impurity. Here, we demonstrate that strongly asymmetric Friedel oscillations occur if the system is far from the equilibrium. We discuss how this asymmetry depends on the model parameters and the difference of the temperatures of the leads (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

On the CTMA for the infinite U Anderson impurity model

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 7 2007
Hellmut Keiter
Abstract If one wants to deal with strongly correlated electron lattice systems within dynamical mean field theory, one needs an impurity solver, i.e. a solution for the dynamics of the Anderson magnetic impurity problem. The most ambitious approach to that problem has been the consistent t-matrix approximation (CTMA). The basic integral equations could be solved with a slow variable approximation, which compared well with a direct numerical solution. Fermi-liquid behavior was not obtained, presumably the normalscattering potential was treated approximately only. We show, how the normal scattering potential can be included exactly. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Resonant tunneling through a dilute nitride quantum well

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2008
N. Mori
Abstract We have developed a theory for resonant tunneling through a dilute nitride quantum well in the presence of a tilted magnetic field. We show that magneto-tunneling spectroscopy provides a novel means of probing the scattering potential due to randomly distributed nitrogen impurities. This technique can be extended to probe other types and sources of disordered potential. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]