TWO-DIMENSIONAL D- DONOR IN A STRONG MAGNETIC FIELD

2008 ◽  
Vol 22 (26) ◽  
pp. 2579-2585
Author(s):  
XIAOYAN ZHANG ◽  
GUOLIANG FAN ◽  
JINFENG WANG
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Variational Method ◽  
Bound State ◽  
Binding Energies ◽  
Triplet States ◽  
Two Dimensional ◽  
Threshold Values ◽  
Spin Triplet ◽  
The Magnetic Field

Two-dimensional negative donor ion in magnetic fields are investigated. Using a variational method, we calculated the binding energies of D- center for the spin-triplet states of L = -2 and L = -3 in this structure. The threshold values of the magnetic field which turn unbound state into bound state were obtained.

On the stability of parallel flows with parallel magnetic fields

1966 ◽  
Vol 293 (1434) ◽  
pp. 342-358 ◽  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Parallel Magnetic Field ◽  
Parallel Flows ◽  
The Mean ◽  
The Stability ◽  
The Magnetic Field ◽  
Parallel Magnetic Fields

The first part of the paper is a physical discussion of the way in which a magnetic field affects the stability of a fluid in motion. Particular emphasis is given to how the magnetic field affects the interaction of the disturbance with the mean motion. The second part is an analysis of the stability of plane parallel flows of fluids with finite viscosity and conductivity under the action of uniform parallel magnetic fields. We show that, in general, three-dimensional disturbances are the most unstable, thus disagreeing with the conclusion of Michael (1953) and Stuart (1954). We show how results obtained for two-dimensional disturbances can be used to calculate the most unstable three-dimensional disturbances and thence we prove that a parallel magnetic field can never completely stabilize a parallel flow.

scholarly journals Band functions in the presence of magnetic steps

2015 ◽  
Vol 26 (01) ◽  
pp. 161-184 ◽  
Author(s):  
P. D. Hislop ◽  
N. Popoff ◽  
N. Raymond ◽  
M. P. Sundqvist
Keyword(s):  
Magnetic Field ◽  
Asymptotic Expansion ◽  
Magnetic Fields ◽  
Essential Spectrum ◽  
Effective Potential ◽  
Explicit Description ◽  
Natural Order ◽  
Two Dimensional ◽  
Piecewise Constant ◽  
The Magnetic Field

We complete the analysis of the band functions for two-dimensional magnetic Schrödinger operators with piecewise constant magnetic fields. The discontinuity of the magnetic field can create edge currents that flow along the discontinuity, which have been described by physicists. Properties of these edge currents are directly related to the behavior of the band functions. The effective potential of the fiber operator is an asymmetric double well (eventually degenerated) and the analysis of the splitting of the bands incorporates the asymmetry. If the magnetic field vanishes, the reduced operator has essential spectrum and we provide an explicit description of the band functions located below the essential spectrum. For non-degenerate magnetic steps, we provide an asymptotic expansion of the band functions at infinity. We prove that when the ratio of the two magnetic fields is rational, a splitting of the band functions occurs and has a natural order, predicted by numerical computations.

scholarly journals Self-magnetic field calculations in ray-tracing codes

2000 ◽  
Vol 18 (4) ◽  
pp. 601-610 ◽  
Author(s):  
STANLEY HUMPHRIES ◽  
JOHN PETILLO
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Ray Tracing ◽  
Field Calculation ◽  
Two Dimensional ◽  
Magnetic Forces ◽  
Iteration Cycle ◽  
Simple Rules ◽  
The Magnetic Field ◽  
Limited Accuracy

Beam-generated magnetic fields strongly influence the behavior of relativistic electron guns. Existing methods used in ray-tracing codes have limited accuracy and may not correctly represent nonlaminar beams. We describe a technique for the magnetic field calculation in a two-dimensional code based on the assignment of particle currents to the faces of elements in the mesh used for the electrostatic calculation. The balanced calculation of electric and magnetic forces in the same iteration cycle reduces the possibility of numerical filamentation instabilities. With simple rules of assignment on boundary faces, the method also handles field contributions of electrode currents. Several benchmark calculations performed on conformal meshes illustrate the versatility of the technique.

scholarly journals Modeling of Two-Dimensional Light Bullets Propagation in an Array of Carbon Nanotubes Taking into Account the Mechanical Tension and Magnetic Field

2020 ◽  
pp. 36-44
Author(s):  
Natalia Konobeeva ◽  
Dmitry Skvortsov
Keyword(s):  
Magnetic Field ◽  
Carbon Nanotubes ◽  
Gauge Theory ◽  
Magnetic Fields ◽  
Electronic Spectrum ◽  
Acoustic Field ◽  
Two Dimensional ◽  
Mechanical Tension ◽  
Light Bullet ◽  
The Magnetic Field

In this paper, we study the influence of acoustic and magnetic fields on the propagation of twodimensional light bullet in an array of carbon nanotubes. The acoustic field is taken into account in the framework of the gauge theory. A magnetic field is applied along the nanotube axis and leads to a change in the electronic spectrum of ?electrons. It is shown, that the pulse stably propagates in the medium, taking into account both of these factors. In this case, the magnetic field and tension slows down the pulse, as well as changes its amplitude.

POLARON CORRECTION TO THE NEGATIVE DONOR ON THE HETERO-INTERFACE IN MAGNETIC FIELDS (II–VI CRYSTALS)

2003 ◽  
Vol 17 (31n32) ◽  
pp. 6097-6107 ◽  
Author(s):  
XIAOYAN ZHANG ◽  
XU WANG ◽  
GUOLIANG FAN
Keyword(s):  
Magnetic Fields ◽  
Variational Method ◽  
Triplet State ◽  
Numerical Results ◽  
Binding Energies ◽  
Phonon Coupling ◽  
Polar Crystal ◽  
Spin Triplet

Negative donor ion on the hetero-interface in magnetic fields are investigated. Using a variational method, we have calculated the binding energies of D- center for the spin-triplet state of L=-1 in this structure. Moreover, the effect of electron-interface phonon coupling on the energy of a donor located in a polar-crystal hetero-interface is found. Numerical results are produced for heterostructures of some II–VI crystals.

INFLUENCE OF MAGNETIC FIELDS ON THE INTRINSIC SPIN HALL EFFECT IN TWO-DIMENSIONAL SYSTEMS

2009 ◽  
Vol 23 (12n13) ◽  
pp. 2566-2572 ◽  
Author(s):  
O. E. RAICHEV
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Hall Effect ◽  
Berry Phase ◽  
Zeeman Splitting ◽  
Hall Conductivity ◽  
Spin Hall Effect ◽  
Two Dimensional ◽  
The Magnetic Field ◽  
Spin Hall Conductivity

The influence of magnetic fields on the electron spin in solids involves two basic mechanisms. First, any magnetic field introduces the Zeeman splitting of electron states, thereby modifying spin precession. Second, since the magnetic field affects the electron motion in the plane perpendicular to the field, the spin dynamics is also modified, owing to the spin-orbit interaction. The theory predicts, as a consequence of this influence, unusual properties of the intrinsic spin-Hall effect in two-dimensional systems in the presence of magnetic fields. This paper describes non-monotonic dependence of the spin-Hall conductivity on the magnetic field and its enhancement in the case of weak disorder, as well as multiple jumps of the spin-Hall conductivity owing to the topological transitions (abrupt changes of the Berry phase) induced by the parallel magnetic field.

FREE AND DONOR-BOUND CHARGED MAGNETOEXCITONS IN QUANTUM WELLS

2007 ◽  
Vol 21 (08n09) ◽  
pp. 1563-1567 ◽  
Author(s):  
ALEXANDER B. DZYUBENKO ◽  
DIANA A. COSMA ◽  
ANDREY Yu. SIVACHENKO
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Quantum Wells ◽  
Singlet State ◽  
Optical Transitions ◽  
Two Dimensional ◽  
Spin Singlet ◽  
Spin Triplet ◽  
Distinct Features ◽  
The Magnetic Field

We consider eigenstates and magneto-optical transitions of free and donor-bound spin-singlet and spin-triplet charged magnetoexcitons in quasi-two-dimensional quantum wells. We show that the bright singlet state remains always bound while spin-triplet dark and bright states become unbound when the distance to the donor ion becomes smaller than certain critical values, which depend on the magnetic field strength. We demonstrate that main magneto-photoluminescence lines of free and donor-bound charged excitons exhibit very similar features. However, shake-up processes in photoluminescence of free trions are strictly prohibited. Therefore, shake-up transitions are distinct features indicating that symmetry-breaking mechanisms are present in the system.

Matter in superstrong magnetic fields

1986 ◽  
Vol 64 (3) ◽  
pp. 256-268 ◽  
Author(s):  
J. E. Skjervold ◽  
E. Østgaard
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Variational Method ◽  
Cohesive Energy ◽  
Condensed Matter ◽  
Binding Energies ◽  
Free Atoms ◽  
The Difference ◽  
Cohesive Energies

The behaviour of condensed matter in superstrong magnetic fields of the order of 1012–1015 G is investigated, i.e., binding energies of atoms in condensed matter are calculated by a variational method. The cohesive energy, i.e., the difference between the binding energies of free atoms and of atoms in condensed matter, is also calculated, and results are obtained for hydrogen, helium, carbon, oxygen, silicon, and iron atoms.For a magnetic field of 1012 G, we obtain binding energies for atoms in condensed matter of 0.2 keV for hydrogen, 0.7 keV for helium, 4.5 keV for carbon, 7.4 keV for oxygen, 20.0 keV for silicon, and 59.0 keV for iron. For a magnetic field of 1014 G, we get corresponding binding energies of 1.2 keV for hydrogen, 3.9 keV for helium, 27.0 keV for carbon, 44.9 keV for oxygen, 121.5 keV for silicon, and 366 keV for iron. For a magnetic field of 1012 G, we obtain cohesive energies of 0.04 keV for hydrogen, 0.10 keV for helium, 0.36 keV for carbon, 0.51 keV for oxygen, 1.4 keV for silicon, and 2.8 keV for iron. For a magnetic field of 1014 G, we get corresponding cohesive energies of 0.16 keV for hydrogen, 0.40 keV for helium, 1.9 keV for carbon, 3.0 keV for oxygen, 7.3 keV for silicon, and 19.4 keV for iron.

Three-dimensional MHD flows in rectangular ducts with internal obstacles

2000 ◽  
Vol 418 ◽  
pp. 265-295 ◽  
Author(s):  
B. MÜCK ◽  
C. GÜNTHER ◽  
U. MÜLLER ◽  
L. BÜHLER
Keyword(s):  
Magnetic Field ◽  
Numerical Simulation ◽  
Reynolds Number ◽  
Magnetic Fields ◽  
Interaction Parameter ◽  
Hartmann Number ◽  
Three Dimensional ◽  
Side Length ◽  
Two Dimensional ◽  
The Magnetic Field

This paper presents a numerical simulation of the magnetohydrodynamic (MHD) liquid metal flow around a square cylinder placed in a rectangular duct. In the hydrodynamic case, for a certain parameter range the well-known Kármán vortex street with three-dimensional flow patterns is observed, similar to the flow around a circular cylinder. In this study a uniform magnetic field aligned with the cylinder is applied and its influence on the formation and downstream transport of vortices is investigated. The relevant key parameters for the MHD flow are the Hartmann number M, the interaction parameter N and the hydrodynamic Reynolds number, all based on the side length of the cylinder. The Hartmann number M was varied in the range 0 [les ] M [les ] 85 and the interaction parameter N in the range 0 [les ] N [les ] 36. Results are presented for two fixed Reynolds numbers Re = 200 and Re = 250. The magnetic Reynolds number is assumed to be very small. The results of the numerical simulation are compared with known experimental and theoretical results. The hydrodynamic simulation shows characteristic intermittent pulsations of the drag and lift force on the cylinder. At Re = 200 a mix of secondary spanwise three-dimensional instabilities (A and B mode, rib vortices) could be observed. The spanwise wavelength of the rib vortices was found to be about 2–3 cylinder side lengths in the near wake. At Re = 250 the flow appears more organized showing a regular B mode pattern and a spanwise wavelength of about 1 cylinder side length. With an applied magnetic field a quasi-two-dimensional flow can be obtained at low N ≈ 1 due to the strong non-isotropic character of the electromagnetic forces. The remaining vortices have their axes aligned with the magnetic field. With increasing magnetic fields these vortices are further damped due to Hartmann braking. The result that the ‘quasi-two-dimensional’ vortices have a curvature in the direction of the magnetic field can be explained by means of an asymptotic analysis of the governing equations. With very high magnetic fields the time-dependent vortex shedding can be almost completely suppressed. By three-dimensional visualization it was possible to show characteristic paths of the electric current for this kind of flow, explaining the action of the Lorentz forces.

scholarly journals Semiclassical bounds in magnetic bottles

2016 ◽  
Vol 28 (01) ◽  
pp. 1650002 ◽  
Author(s):  
Diana Barseghyan ◽  
Pavel Exner ◽  
Hynek Kovařík ◽  
Timo Weidl
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Dirichlet Boundary ◽  
Three Dimensional ◽  
Local Change ◽  
Two Dimensional ◽  
Magnetic Systems ◽  
Spectral Estimates ◽  
The Magnetic Field

The aim of the paper is to derive spectral estimates into several classes of magnetic systems. They include three-dimensional regions with Dirichlet boundary as well as a particle in [Formula: see text] confined by a local change of the magnetic field. We establish two-dimensional Berezin–Li–Yau and Lieb–Thirring-type bounds in the presence of magnetic fields and, using them, get three-dimensional estimates for the eigenvalue moments of the corresponding magnetic Laplacians.

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