Magneto-Spectroscopy of Two-Electron Transitions in Homoepitaxial GaN.

2001 ◽  
Vol 693 ◽  
Author(s):  
M. Wojdak ◽  
J.M. Baranowski ◽  
A. Wysmolck ◽  
K. Pakula ◽  
R. Stepnicwski ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Excited State ◽  
Magnetic Fields ◽  
Effective Mass ◽  
Electron Energy ◽  
Electron Transition ◽  
Electron Effective Mass ◽  
Neutral Donor ◽  
Electron Transitions ◽  
The Difference

AbstractTwo-electron transition occurs when the exciton bound to a neutral donor (DBE) recombines and leaves the donor in an excited state. The two-electron energy is therefore lower than that of the DBE peak by the difference in ground and excited state of the neutral donor. In a magnetic field the two-electron satellite splits into several components. These intra-donor excitations have been studied in homoepitaxial GaN up to magnetic fields reaching 23T. For Faraday (B‖c) configuration the two-electron transition splits mainly into 2s, 2p0, 2p+ and 2p- components. The total splitting between 2p+ and 2p- is equal to Landau energy. For Voigt (B???c) configuration in addition to transition to 2s, 2p0, 2p- and 2p+ there are additional lines which origin is discussed. It has been found that for two configurations of magnetic field the separation between 2p+ and 2p- is not exactly equal, what indicates the anisotropy of the electron effective mass. It has been found that m| = 0.205m0 and m??? = 0.225m0.

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.

Effect of Magnetic Fields on the Resistance and Microstructure of Al-Cu Alloy during Solidification Processing

2011 ◽  
Vol 287-290 ◽  
pp. 2916-2920
Author(s):  
Chun Yan Ban ◽  
Peng Qian ◽  
Xu Zhang ◽  
Qi Xian Ba ◽  
Jian Zhong Cui
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Turning Points ◽  
Probe Method ◽  
Solidification Processing ◽  
Ac Magnetic Field ◽  
Dc Magnetic Field ◽  
Cu Alloy ◽  
The Difference ◽  
Good Agreement

The resistance of Al-21%Cu alloy under no magnetic field, DC magnetic field and AC magnetic field from liquid to solid was measured by a four-probe method. The difference of resistance versus temperature curves (R-T curves) was analyzed. It is found that the R-T curves of Al-21%Cu alloy are monotone decreasing and have two obvious turning points. Under DC magnetic field, the liquidus and solidus temperatures of the alloy both decrease, while under AC magnetic field, the liquidus and solidus temperatures both increase. There is a good agreement between the microstructure of quenching sample and R-T curves. The mechanism of the effect of magnetic fields was discussed.

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.

scholarly journals Strongly Magnetized Sources: QED and X-ray Polarization

Galaxies ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 76 ◽  
Author(s):  
Jeremy Heyl ◽  
Ilaria Caiazzo
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
First Principles ◽  
Quantum Electrodynamics ◽  
Polarization State ◽  
Radiative Corrections ◽  
Strong Magnetic Fields ◽  
X Ray ◽  
The Difference

Radiative corrections of quantum electrodynamics cause a vacuum threaded by a magnetic field to be birefringent. This means that radiation of different polarizations travels at different speeds. Even in the strong magnetic fields of astrophysical sources, the difference in speed is small. However, it has profound consequences for the extent of polarization expected from strongly magnetized sources. We demonstrate how the birefringence arises from first principles, show how birefringence affects the polarization state of radiation and present recent calculations for the expected polarization from magnetars and X-ray pulsars.

Study on the Solidification Structures of Al-Fe-Si Alloy under DC and AC Magnetic Fields

2011 ◽  
Vol 189-193 ◽  
pp. 4477-4482
Author(s):  
Chun Yan Ban ◽  
Xu Zhang ◽  
Peng Qian ◽  
Yi Han ◽  
Jian Zhong Cui
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Chinese Script ◽  
Minor Amount ◽  
Fine Needle ◽  
Ac Magnetic Field ◽  
Dc Magnetic Field ◽  
Conventional Condition ◽  
The Difference ◽  
Al Matrix

The effects of DC and AC magnetic field on the phase composition, morphology and distribution of the ternary Al-Fe-Si alloy were investigated. The solidification structures of the alloy solidified with and without the application of magnetic fields were confirmed by DSC and structural measurements. The results showed that, in this Al-Fe-Si alloy the fine needle-like Al3Fe phase dominated the microstructure at the grain boundaries with the minor amount of Chinese script-like α-AlFeSi. Distribution of Al3Fe phase was almost homogeneous in the volume of the sample when alloy was solidified in the conventional condition. When the DC magnetic field was imposed, distribution of Al3Fe phase was more homogeneous. However, the Al3Fe and α-AlFeSi phases were accumulated towards the center of the sample with the application of the AC magnetic field. This is due to the difference of Lorentz force between Al matrix and iron-containing intermetallics. Furthermore, the amount of Chinese script-like α-AlFeSi was increased remarkably under AC magnetic field.

NONLINEAR CURRENT DENSITY IN QUANTUM WELLS WITH PARABOLIC POTENTIAL UNDER CROSSED ELECTRIC AND MAGNETIC FIELDS

2012 ◽  
Vol 01 (02) ◽  
pp. 1250021
Author(s):  
BUI DINH HOI ◽  
TRAN CONG PHONG
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Electric Field ◽  
Quantum Wells ◽  
Effective Mass ◽  
Current Density ◽  
Electrical Transport ◽  
Physical Parameters ◽  
Electric And Magnetic Fields ◽  
Dc Electric Field

The DC electrical transport in a quantum well (QW) with parabolic confinement potential [Formula: see text] (where m and ωz are the effective mass of electron and the confinement frequency in z direction, respectively) subjected to a crossed DC electric field and magnetic field, is studied theoretically. The scattering by optical phonons is taken into account at high temperatures and strong magnetic fields. We obtained the expression for nonlinear current density (NCD) involving external (electric and magnetic) fields and characteristic parameters of QW. The dependence of NCD on the DC electric field is complicated. The analytical result is computationally evaluated and graphically plotted for a specific parabolic QW of GaAs / AlGaAs . The numerical results show the appearance of maximum peaks satisfying the condition of intersubband magnetophonon resonance (MPR) effect in the presence of a DC electric field. Especially, we show that the effect can be applied in experiment to determine some physical parameters by using magnetic field, such as the numbers of Landau levels for which electrons transfer, the effective mass, the charge of electrons or the confinement frequency characterized for PQW.

scholarly journals SUTHERLAND-EINSTEIN HYPOTHESIS ON THE ORIGIN OF MAGNETIC FIELDS IN ASTROPHYSICAL OBJECTS

Metaphysics ◽  
2020 ◽  
pp. 166-174
Author(s):  
I. A Babenko
Keyword(s):  
Magnetic Field ◽  
Twentieth Century ◽  
Magnetic Fields ◽  
Field Experiments ◽  
The Earth ◽  
Astrophysical Objects ◽  
The Difference ◽  
Rotation Of The Earth

The article discusses the theoretical and experimental foundations of the hypothesis on the origin the magnetic field's the Earth's and other astrophysical objects, put forward at the beginning of the twentieth century by Sutherland and Einstein. According to this hypothesis, the different of the electric charg of the electron and proton and the rotation of the Earth (astronomical), leads to the appearance of a magnetic field. Experiments under terrestrial conditions aimed at determining the difference between the electric charges of an electron and a proton are discussed.

Transporteigenschaften und Quantenoszillationen von Te-und Sn-dotiertem Bi94Sb6 / Transport Properties and Quantum Oscillations of Te- and Sn-Doped Bi94Sb6

1975 ◽  
Vol 30 (8) ◽  
pp. 1071-1083
Author(s):  
G. Schneider ◽  
R. Trommer
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Transport Properties ◽  
Thermoelectric Power ◽  
Effective Mass ◽  
Quantum Oscillations ◽  
Mobility Tensor ◽  
Mass Tensor ◽  
Approximate Composition ◽  
Shubnikov De Haas Oscillations

Abstract Electronic transport properties of undoped, Te- and Sn-doped Bi-Sb-alloys of approximate composition Bi94Sb6 were measured within the temperature range 10-300 K. Besides the electrical conductivity and thermoelectric power the magnetoresistance, the Hall effect and the thermoelectric power in a magnetic field were investigated. Measurements in low magnetic fields yield the mobility tensor for Te-doped samples and in connection with the Shubnikov-de Haas oscillations in higher magnetic fields the effective mass tensor of the electrons. Corresponding investigations on Sn-doped p-conducting samples in this paper give the mobility tensors of light and heavy holes and approximately the effective mass tensor. Here quantum oscillations of the thermoelectric power in a magnetic field were analysed.

LBA high resolution observations of ground- and excited-state OH masers towards G351.417+0.645

2017 ◽  
Vol 13 (S336) ◽  
pp. 329-330
Author(s):  
T. Chanapote ◽  
K. Asanok ◽  
R. Dodson ◽  
M. Rioja ◽  
J. A. Green ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Excited State ◽  
Magnetic Fields ◽  
Massive Star ◽  
State Transitions ◽  
Spatial Gradient ◽  
Star Forming ◽  
Physical Conditions ◽  
Long Baseline ◽  
Field Strengths

AbstractWe present the results from the Australian Long Baseline Array (LBA) observations of the ground- and excited-state OH masers at high resolutions towards the massive star-forming region G351.417+0.645 in 2012. We obtain the most accurate spatial gradient of magnetic fields at ground state transitions and verify the reliability of magnetic field strengths measured from previous lower resolution observations. In comparison with previous LBA observations in 2001 at 6.0 GHz, we identified several matched Zeeman pairs. We found that the OH maser features have no significant change of magnetic field strengths and directions with small internal proper motions, implying quite stable physical conditions. Additionally, we found that 1665- and 6035-MHz OH maser features reveal the same trend of reversal of magnetic fields. Moreover, we also analyzed the physical conditions at different locations from the coincidence of different OH maser transitions based on current OH maser models.

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