Zeeman splitting, Zeeman transitions and optical absorption of an electron confined in spherical quantum dots under the magnetic field

A theoeritical study on the effect of a magnetic field or impurities on the carries states of self-assembled quantum dots is presented. The magnetic field is applied along the growth direction of the dots, and for comparison two systems are considered, InAs embeded in GaAs, and GaN in AlN. The electronic states and energy are calculated in the framework of the k.p theory in 8 bands including the strain and piezoelectric effects. Zeeman splitting and anticrossings are observed in InAs/GaAs, while the field introduces small changes in the nitrides. It is also included a study about hidrogen-like impurities, which may be negative or positive. It is noted that depending on the type of impurity, the confinement energy of carriers is changed, and the distribution of the probability density of the carriers is affected too.

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Control of optical absorption nonlinearity in multi-layers quantum dots and rings

International Journal of Modern Physics B ◽

10.1142/s0217979218500078 ◽

2018 ◽

Vol 32 (02) ◽

pp. 1850007

Author(s):

M. Solaimani ◽

Leila Lavaei

Keyword(s):

Magnetic Field ◽

Quantum Dots ◽

Optical Properties ◽

Optical Absorption ◽

Absorption Coefficient ◽

Quantum Ring ◽

Ring Radius ◽

Constant Radius ◽

The Magnetic Field

In this paper, we study the effect of the number of wells, inner (R[Formula: see text]) and outer (R[Formula: see text]) quantum ring radiuses, and magnetic field as controlling tools to change the nonlinearity in optical properties of GaN/AlN constant radius multi-layer quantum dots and rings. It is seen that for small R[Formula: see text] and for fixed R[Formula: see text] and R[Formula: see text], by increasing the number of wells, the nonlinearity increases, while for greater R[Formula: see text] and for fixed R[Formula: see text] and R[Formula: see text], by increasing the number of wells the nonlinearity first decreases and then increases. For systems with greater R[Formula: see text], the nonlinearity continually increases by increasing the number of wells. For fixed R[Formula: see text], the critical well number, in which the nonlinearity changes its behavior, decreases by increasing the inner quantum ring radius R[Formula: see text]. The absorption coefficient does not undertake any blue or red shifts by changing the number of wells. In the systems with more number of wells, the nonlinearity reduces more rapidly by increasing the magnetic field. Finally, by increasing the radius R[Formula: see text], the nonlinearity increases.

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The magnetic field in the dense photodissociation region of DR 21

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3898 ◽

2020 ◽

Author(s):

Atanu Koley ◽

Nirupam Roy ◽

Karl M Menten ◽

Arshia M Jacob ◽

Thushara G S Pillai ◽

...

Keyword(s):

Magnetic Field ◽

Field Strength ◽

Zeeman Effect ◽

Zeeman Splitting ◽

Weak Field ◽

Field Energy ◽

Evolutionary Stage ◽

Maser Emission ◽

The Magnetic Field ◽

Photodissociation Region

Abstract Measuring interstellar magnetic fields is extremely important for understanding their role in different evolutionary stages of interstellar clouds and of star formation. However, detecting the weak field is observationally challenging. We present measurements of the Zeeman effect in the 1665 and 1667 MHz (18 cm) lines of the hydroxyl radical (OH) lines toward the dense photodissociation region (PDR) associated with the compact H ii region DR 21 (Main). From the OH 18 cm absorption, observed with the Karl G. Jansky Very Large Array, we find that the line of sight magnetic field in this region is ∼0.13 mG. The same transitions in maser emission toward the neighbouring DR 21(OH) and W 75S-FR1 regions also exhibit the Zeeman splitting. Along with the OH data, we use [C ii] 158 μm line and hydrogen radio recombination line data to constrain the physical conditions and the kinematics of the region. We find the OH column density to be ∼3.6 × 1016(Tex/25 K) cm−2, and that the 1665 and 1667 MHz absorption lines are originating from the gas where OH and C+ are co-existing in the PDR. Under reasonable assumptions, we find the measured magnetic field strength for the PDR to be lower than the value expected from the commonly discussed density–magnetic field relation while the field strength values estimated from the maser emission are roughly consistent with the same. Finally, we compare the magnetic field energy density with the overall energetics of DR 21’s PDR and find that, in its current evolutionary stage, the magnetic field is not dynamically important.

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Investigation of Light Absorption in a ZnS Quantum Dot

Journal of Spectroscopy ◽

10.1155/2013/850352 ◽

2013 ◽

Vol 2013 ◽

pp. 1-4 ◽

Cited By ~ 3

Author(s):

Hojjatollah K. Salehani ◽

Maedeh Zakeri

Keyword(s):

Magnetic Field ◽

Optical Absorption ◽

Quantum Dot ◽

Excited States ◽

Light Absorption ◽

Blue Shift ◽

Optical Absorption Coefficient ◽

Parabolic Confinement ◽

Parabolic Confinement Potential ◽

The Magnetic Field

The light absorption of a ZnS quantum dot with a parabolic confinement potential is studied in this paper in the presence of magnetic field perpendicular to dot plane. The Schrodinger equation of a single electron is solved numerically, and energy spectra and wave functions are obtained. Then, the optical absorption coefficients in transition from ground state to different excited states are calculated. The effects the magnetic field and quantum dot width on the optical absorption are investigated. It is found that the optical absorption coefficient has a blue shift by increasing of magnetic field or confinement strength of quantum dot.

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The Magnetic Field Near the Local Bubble

International Astronomical Union Colloquium ◽

10.1017/s0252921100071037 ◽

1997 ◽

Vol 166 ◽

pp. 227-238

Author(s):

Carl Heiles

Keyword(s):

Magnetic Field ◽

Large Scale ◽

Zeeman Splitting ◽

Relativistic Electrons ◽

Local Bubble ◽

Scale Field ◽

Large Scale Field ◽

Field Lines ◽

Hi Shells ◽

The Magnetic Field

AbstractThere are almost no direct observational indicators of the magnetic field inside the local bubble. Just outside the bubble, the best tracers are stellar polarization and HI Zeeman splitting. These show that the local field does not follow the large-scale Galactic field. Here we discuss whether the deformation of the large-scale field by the local HI shells is consistent with the observations. We concentrate on the Loop 1 region, and find that the field lines are well-explained by this idea; in addition, the bright radio filaments of Radio Loop 1 delineate particular field lines that are “lit up” by an excess of relativistic electrons.

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Magnetic Fields in OH Maser Clouds

Symposium - International Astronomical Union ◽

10.1017/s0074180900026565 ◽

1974 ◽

Vol 60 ◽

pp. 275-292 ◽

Cited By ~ 1

Author(s):

R. D. Davies

Keyword(s):

Magnetic Field ◽

Angular Momentum ◽

Magnetic Fields ◽

Magnetic Flux ◽

Field Data ◽

Zeeman Splitting ◽

Galactic Rotation ◽

Magnetic Field Data ◽

The Magnetic Field ◽

Maser Sources

Observations of Class I OH maser sources show a range of features which are predicted on the basis of Zeeman splitting in a source magnetic field. Magnetic field strengths of 2 to 7 mG are derived for eight OH maser sources. The fields in all the clouds are directed in the sense of galactic rotation. A model of W3 OH is proposed which incorporates the magnetic field data. It is shown that no large amount of magnetic flux or angular momentum has been lost since the condensation from the interstellar medium began.

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