Electron Subband Levels of n-Type δ-Doped Quantum Wells under In-Plane Magnetic Fields

1997 ◽  
Vol 11 (09) ◽  
pp. 1195-1207
Author(s):  
E. K. Takahashi ◽  
A. T. Lino ◽  
L. M. R. Scolfaro
Keyword(s):  
Magnetic Field ◽  
Electronic Structure ◽  
Magnetic Fields ◽  
Quantum Well ◽  
Quantum Wells ◽  
Conduction Band ◽  
Electron Energy ◽  
Self Consistent ◽  
Plane Direction ◽  
The Magnetic Field

Self-consistent calculations of the electronic structure of center n-δ-doped GaAs/Al x Ga 1-x As quantum wells under in-plane magnetic fields are presented. The field B is varied up to 20 Tesla for different quantum well widths L w and sheet donor concentrations N D . The magnetic field produces noticeable changes in the energy dispersions along an in-plane direction perpendicular to B. The effects of B are more pronounced for higher electronic subbands. It is found that the diamagnetic shifts increase with increasing L w and/or N D . Contrarily to what has been observed in modulation-doped quantum wells, in these δ-doped systems the electron energy dispersions keep the single conduction band minimum at the center of the Brillouin zone even for intense magnetic fields.

Scattering Processes with the Emission of Longitudinal Optical Phonons in the Landau Level System In GaAs/AlGaAs Quantum Well

2021 ◽  
Author(s):  
Ngo Vinh Doan The ◽  
Trung Le Canh
Keyword(s):  
Magnetic Field ◽  
Quantum Well ◽  
Quantum Wells ◽  
Golden Rule ◽  
Longitudinal Optical ◽  
Optical Phonons ◽  
Scattering Rate ◽  
Quantizing Magnetic Field ◽  
Scattering Time ◽  
The Magnetic Field

Abstract The scattering processes of longitudinal optical phonons in GaAs/AlGaAs quantum wells in a quantizing magnetic field are considered. The time of intrasubband scattering between Landau levels is calculated by using Fermi's golden rule. The dependence of the scattering rate on the magnitude of the magnetic field has been shown and the magnetic field can suppress scattering processes on longitudinal optical phonons. It is found that the scattering time depends linearly on the width of the quantum well.

Electron in a Quantum Wire in the Presence of Parallel and Perpendicular Magnetic Fields

2013 ◽  
Vol 380-384 ◽  
pp. 4837-4840
Author(s):  
Xiu Zhi Duan ◽  
Guang Xin Wang
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Effective Mass ◽  
Electron Energy ◽  
Quantum Wire ◽  
Quantum Wires ◽  
Electron States ◽  
Mass Approximation ◽  
The Magnetic Field ◽  
Rectangular Quantum Wires

The electron states of self-assembled rectangular quantum wires (QWRs) are investigated in detail in the presence of a magnetic field. The calculations are done in the single band effective mass approximation. We study the electron states for the magnetic fields applied along and perpendicular to the wire, taking into account the different masses of the various particles inside and outside the QWRs. The electron energy and the influence of the magnetic field are discussed in this paper.

COMPREHENSIVE STUDY OF SPIN-FLIP EXCITATIONS IN CdZnTe/CdZnMnTe QUANTUM WELLS

2007 ◽  
Vol 21 (08n09) ◽  
pp. 1610-1614
Author(s):  
DAISUKE FUKUOKA ◽  
KOUSHIRO ARAHARA ◽  
TAKAAKI KOYAMA ◽  
NAOKI TANAKA ◽  
KENICHI OTO ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Quantum Well ◽  
Quantum Wells ◽  
Electron Spin ◽  
Energy Difference ◽  
Magnetic Field Direction ◽  
Kerr Rotation ◽  
Spin Configuration ◽  
Spin Flip ◽  
The Magnetic Field

Spin-flip excitations in non-doped Cd 0.93 Zn 0.07 Te/Cd 0.48 Zn 0.04 Mn 0.48 Te quantum wells have been comprehensively studied by spin-flip Raman scattering (SFRS) spectroscopy and time-resolved Kerr rotation (TRKR) spectroscopy. In 4 nm quantum well, two spin-flip Raman peaks were observed in addition to the multiple Mn 2+ spin-flip scatterings. The spin-flip energies are isotropic against the magnetic field direction and well described by modified Brillouin functions. Based on the circumstantial analysis, they are assigned to the spin-flip of residual electrons and the electron spin-flip in the localized exciton, respectively, even though the large energy difference between the two electron spin-flip processes is a puzzle. While, in 9 nm quantum well a strange spin-flip excitation was observed together with a very weak Mn 2+ spin-flip scattering. The spin-flip energy changed strangely up to the magnetic field 4T, and then linearly increased with field (| g *|=1.15). A high-resolution TRKR spectroscopy revealed an unusual temperature dependence, which resembled "softening mode" of spin resonance observed in p-doped ferromagnetic CdMnTe quantum wells. However, these behaviors are well understood by an "inverted spin configuration", which results from a negative g*-factor and a very weak s-d interaction between the electrons and the manganese ions in the barrier.

OPTICAL PROPERTIES OF ACCEPTORS IN SEMIMAGNETIC QUANTUM WELL SYSTEMS

2002 ◽  
Vol 16 (25) ◽  
pp. 3737-3757 ◽  
Author(s):  
Sr. GERARDIN JAYAM ◽  
K. NAVANEETHAKRISHNAN
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Quantum Well ◽  
Cross Sections ◽  
Empirical Relationship ◽  
Phonon Interaction ◽  
Shallow Acceptor ◽  
Electron Phonon Interaction ◽  
The Magnetic Field ◽  
Confined Phonons

The binding energy of a shallow acceptor in an isolated quantum well of the CdTe / Cd 1-x Mn x Te system has been investigated in an external magnetic field, assuming an empirical relationship between the barrier height and the magnetic field. Photoionization cross-sections for different magnetic fields have been estimated. Taking into account the confined phonons in the electron-phonon interaction, carrier capture times for various magnetic fields and different hydrostatic pressures have been computed. The results obtained are discussed in the light of the existing literature.

BULK NONPARABOLIC EFFECTIVE MASS APPLIED TO CALCULATION OF LANDAU LEVEL ENERGY AND COMPARISON WITH CYCLOTRON RESONANCE IN InGaAs/InAlAs QUANTUM WELLS

2004 ◽  
Vol 18 (27n29) ◽  
pp. 3835-3838
Author(s):  
NOBUO KOTERA ◽  
KOICHI TANAKA ◽  
NOBORU MIURA
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Effective Mass ◽  
Conduction Band ◽  
Electron Energy ◽  
Landau Level ◽  
Cyclotron Resonance ◽  
Energy Calculation ◽  
Level Energy ◽  
Band Nonparabolicity

Observation of band nonparabolicity is difficult because the electron energy in conduction band cannot be controlled widely. Using quantization energy in quantum well (QW) where the eigen energy is changed by QW thickness, nonparabolic effective mass inside a single QW of InGaAs was determined recently, up to 0.5 eV above bandedge. The dependence of effective mass on energy was analyzed and applied to calculate Landau level energy. Calculation fit well with cyclotron resonance experiments. Coupling between skew and normal cyclotron resonance was identified by this analysis.

Energy behavior with magnetic field of negatively charged magnetoexcitons in quantum wells and heterojunctions

1999 ◽  
Vol 588 ◽  
Author(s):  
F. M. Munteanu ◽  
Y. Kim ◽  
C. H. Perry ◽  
D. G. Rickel ◽  
J. A. Simmons ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Quantum Well ◽  
Quantum Wells ◽  
Low Temperatures ◽  
High Magnetic Fields ◽  
Crossing Over ◽  
Sample Geometry ◽  
Energy Behavior

AbstractWe present the results of the magneto-photoluminescence measurements performed on modulation doped GaAs/AlGaAs heterostructures in high magnetic fields (up to 60T) and low temperatures (0.37−1.5K). With increasing magnetic field we observe the formation of the triplet and singlet states of negatively charged magneto-excitons (X−) in addition to the neutral exciton (X0). Their behavior with field strongly depends on the sample geometry. In the case of a modulation doped quantum well (QW) with a well-width of 200A, the and states cross at a magnetic field of about 40T, whereas for a modulation-doped single heterojunction (SHJ) these states show no crossing over the whole range of available fields.

Emergence of Twisted Magnetic Flux Related Sigmoidal Brightening

2000 ◽  
Vol 179 ◽  
pp. 263-264
Author(s):  
K. Sundara Raman ◽  
K. B. Ramesh ◽  
R. Selvendran ◽  
P. S. M. Aleem ◽  
K. M. Hiremath
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Ultra Violet ◽  
Active Regions ◽  
Morphological Properties ◽  
Energy Storage And Conversion ◽  
The Sun ◽  
X Rays ◽  
The Magnetic Field

Extended AbstractWe have examined the morphological properties of a sigmoid associated with an SXR (soft X-ray) flare. The sigmoid is cospatial with the EUV (extreme ultra violet) images and in the optical part lies along an S-shaped Hαfilament. The photoheliogram shows flux emergence within an existingδtype sunspot which has caused the rotation of the umbrae giving rise to the sigmoidal brightening.It is now widely accepted that flares derive their energy from the magnetic fields of the active regions and coronal levels are considered to be the flare sites. But still a satisfactory understanding of the flare processes has not been achieved because of the difficulties encountered to predict and estimate the probability of flare eruptions. The convection flows and vortices below the photosphere transport and concentrate magnetic field, which subsequently appear as active regions in the photosphere (Rust & Kumar 1994 and the references therein). Successive emergence of magnetic flux, twist the field, creating flare productive magnetic shear and has been studied by many authors (Sundara Ramanet al.1998 and the references therein). Hence, it is considered that the flare is powered by the energy stored in the twisted magnetic flux tubes (Kurokawa 1996 and the references therein). Rust & Kumar (1996) named the S-shaped bright coronal loops that appear in soft X-rays as ‘Sigmoids’ and concluded that this S-shaped distortion is due to the twist developed in the magnetic field lines. These transient sigmoidal features tell a great deal about unstable coronal magnetic fields, as these regions are more likely to be eruptive (Canfieldet al.1999). As the magnetic fields of the active regions are deep rooted in the Sun, the twist developed in the subphotospheric flux tube penetrates the photosphere and extends in to the corona. Thus, it is essentially favourable for the subphotospheric twist to unwind the twist and transmit it through the photosphere to the corona. Therefore, it becomes essential to make complete observational descriptions of a flare from the magnetic field changes that are taking place in different atmospheric levels of the Sun, to pin down the energy storage and conversion process that trigger the flare phenomena.

scholarly journals An 84-μG Magnetic Field in a Galaxy at Z=0.692?

2008 ◽  
Vol 4 (S254) ◽  
pp. 95-96
Author(s):  
Arthur M. Wolfe ◽  
Regina A. Jorgenson ◽  
Timothy Robishaw ◽  
Carl Heiles ◽  
Jason X. Prochaska
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Faraday Rotation ◽  
Large Scale ◽  
Dynamo Model ◽  
Magnetic Field Generation ◽  
Interstellar Gas ◽  
Splitting Technique ◽  
Average Value ◽  
The Magnetic Field

AbstractThe magnetic field pervading our Galaxy is a crucial constituent of the interstellar medium: it mediates the dynamics of interstellar clouds, the energy density of cosmic rays, and the formation of stars (Beck 2005). The field associated with ionized interstellar gas has been determined through observations of pulsars in our Galaxy. Radio-frequency measurements of pulse dispersion and the rotation of the plane of linear polarization, i.e., Faraday rotation, yield an average value B ≈ 3 μG (Han et al. 2006). The possible detection of Faraday rotation of linearly polarized photons emitted by high-redshift quasars (Kronberg et al. 2008) suggests similar magnetic fields are present in foreground galaxies with redshifts z > 1. As Faraday rotation alone, however, determines neither the magnitude nor the redshift of the magnetic field, the strength of galactic magnetic fields at redshifts z > 0 remains uncertain.Here we report a measurement of a magnetic field of B ≈ 84 μG in a galaxy at z =0.692, using the same Zeeman-splitting technique that revealed an average value of B = 6 μG in the neutral interstellar gas of our Galaxy (Heiles et al. 2004). This is unexpected, as the leading theory of magnetic field generation, the mean-field dynamo model, predicts large-scale magnetic fields to be weaker in the past, rather than stronger (Parker 1970).The full text of this paper was published in Nature (Wolfe et al. 2008).

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