Phonon-assisted absorption in crossed electric and magnetic fields in direct-band semiconductors. II

1969 ◽  
Vol 47 (5) ◽  
pp. 521-531 ◽  
Author(s):  
I. P. Batra
Keyword(s):  
Magnetic Fields ◽  
Optical Absorption ◽  
Electric Field ◽  
Energy Gap ◽  
Level Structure ◽  
Perturbation Expansion ◽  
Weak Electric Field ◽  
Electric And Magnetic Fields ◽  
Direct Energy ◽  
New Perturbation

In polar semiconductors with direct energy gaps, optical absorption is observed for photons with energies well below that corresponding to the energy gap. It is now established that the absorption tail (Urbach's law) is due to indirect phonon-assisted optical transitions involving the absorption of one or more optical phonons of energy kΘ. In the present paper we have considered the effect of crossed electric and magnetic fields on the optical absorption in that region of the Urbach tail where second order processes are dominant. The experimentally favorable situation involving a weak electric field is investigated. A new perturbation expansion in terms of a dimensionless parameter is developed in this connection and is used to obtain the weak electric field limit. Such a study may be useful in exploring the Landau level structure of the valence and conduction bands separately.

PHONON-ASSISTED MAGNETO ABSORPTION IN DIRECT-BAND SEMICONDUCTORS

1967 ◽  
Vol 45 (10) ◽  
pp. 3401-3410 ◽  
Author(s):  
I. P. Batra ◽  
R. R. Haering
Keyword(s):  
Optical Absorption ◽  
Energy Gap ◽  
Level Structure ◽  
Interband Absorption ◽  
Optical Transitions ◽  
Optical Phonons ◽  
Energy Gaps ◽  
Direct Energy ◽  
Direct Band ◽  
Absorption Tail

In polar semiconductors with direct energy gaps, optical absorption is observed for photons with energies well below that corresponding to the energy gap. It is now established that the absorption tail (Urbach's law) is due to indirect phonon-assisted optical transitions involving the absorption of one or more optical phonons of energy kθ. In the present paper we have considered the effect of a magnetic field on the optical absorption in that region of the Urbach tail where second-order processes are dominant. In contrast to the normal direct interband absorption coefficient, the absorption reflects the Landau level structure of valence band and conduction band separately. A discussion is given of the conditions under which such an effect should be observable.

scholarly journals ANALISIS HUBUNGAN SALURAN TEGANGAN TINGGI LISTRIK TERHADAP JARINGAN SELULAR DI DAERAH GRAHA INDAH TAMBAKBOYO LAMONGAN

JOUTICA ◽  
2019 ◽  
Vol 4 (2) ◽  
pp. 255
Author(s):  
Kemal Farouq Mauladi ◽  
Nurul Fuad
Keyword(s):  
Public Health ◽  
Magnetic Fields ◽  
Electric Field ◽  
Cellular Networks ◽  
Electromagnetic Fields ◽  
Electricity Generation ◽  
Negative Impact ◽  
Electrical Energy ◽  
Electric And Magnetic Fields ◽  
The Impact

Telecommunications technology is developing very rapidly, ranging from users or engineers. The development of smartphone smartphones is also increasingly in demand, so that the use of electricity needs is also increasing. The need for electricity usage has resulted in more standing voltage in some settlements. The establishment of sutet will have a negative impact on public health. In addition, the influence of electrical energy on humans occurs because the electrical energy generated by electricity generation or electricity that is channeled gives rise to electromagnetic fields. The higher the voltage required by an equipment, the greater the electric field that is distributed. Besides that, it can also find ways to reduce the negative impact of the electric and magnetic fields produced by SUTET which impacts the process of the occurrence of electric and magnetic fields on SUTET. From the problems above, the author intends to determine the effect or correlation between the impact of SUTET on cellphone network transmissions or channels. This research can later determine the negative impact caused by SUTET for the surrounding community, and the impact of SUTET radiation on cellular networks.

Ion acceleration by multiple laser pulses and their spontaneous electromagnetic fields in plasma

2008 ◽  
Vol 74 (1) ◽  
pp. 111-118
Author(s):  
FEN-CE CHEN
Keyword(s):  
Magnetic Fields ◽  
Electric Field ◽  
Analytical Model ◽  
Electromagnetic Fields ◽  
Equations Of Motion ◽  
Charged Particles ◽  
Laser Pulses ◽  
The Self ◽  
Electric And Magnetic Fields ◽  
Relativistic Equations

AbstractThe acceleration of ions by multiple laser pulses and their spontaneously generated electric and magnetic fields is investigated by using an analytical model for the latter. The relativistic equations of motion of test charged particles are solved numerically. It is found that the self-generated axial electric field plays an important role in the acceleration, and the energy of heavy test ions can reach several gigaelectronvolts.

Modified Morris-Lecar neuron model: Effects of very low frequency electric fields and of magnetic fields on the local and network dynamics of an excitable media

2021 ◽  
Author(s):  
Karthikeyan Rajagopal ◽  
Irene Moroz ◽  
Balamurali Ramakrishnan ◽  
Anitha Karthikeyan ◽  
Prakash Duraisamy
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Electric Field ◽  
Neuron Model ◽  
Low Noise ◽  
Spiral Waves ◽  
Excitable Media ◽  
Field Frequency ◽  
Electric And Magnetic Fields ◽  
Electric Field Frequency

Abstract A Morris-Lecar neuron model is considered with Electric and Magnetic field effects where the electric field is a time varying sinusoid and magnetic field is simulated using an exponential flux memristor. We have shown that the exposure to electric and magnetic fields have significant effects on the neurons and have exhibited complex oscillations. The neurons exhibit a frequency-locked state for the periodic electric field and different ratios of frequency locked states with respect to the electric field frequency is also presented. To show the impact of the electric and magnetic fields on network of neurons, we have constructed different types of network and have shown the network wave propagation phenomenon. Interestingly the nodes exposed to both electric and magnetic fields exhibit more stable spiral waves compared to the nodes exhibited only to the magnetic fields. Also, when the number of layers are increased the range of electric field frequency for which the layers exhibit spiral waves also increase. Finally the noise effects on the field affected neuron network are discussed and multilayer networks supress spiral waves for a very low noise variance compared against the single layer network.

Photodetachment microscopy of H– ion in time-dependent electric and magnetic fields

2018 ◽  
Vol 96 (9) ◽  
pp. 961-968
Author(s):  
De-hua Wang
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Electric Field ◽  
Interference Pattern ◽  
Current Distribution ◽  
Time Dependent ◽  
Electron Current ◽  
Detector Plane ◽  
Electron Trajectories ◽  
Electric And Magnetic Fields

We examine the dynamics of electrons photodetached from the H– ion in time-dependent electric and magnetic fields for the first time. The photodetachment microscopy patterns caused by a time-dependent gradient electric field and magnetic field have been analyzed in great detail based on the semiclassical theory. The interplay of the gradient electric field and magnetic field forces causes an intricate shape of the electron wave and multiple electron trajectories generated by a fixed energy point source can arrive at a given point on the microchannel-plate detector. The interference effects between these electron trajectories cause the oscillatory structures of the electron probability density and electron current distribution, and a set of concentric interference fringes are found at the detector. Our calculation results suggest that the photodetachment microscopy interference pattern on the detector can be adjusted by the electron energy, magnetic field strength, and position of the detector plane. Under certain conditions, the interference pattern in the electron current distribution might be seen on the detector plane localized at a macroscopic distance from the photodetachment source, which can be observed in an actual photodetachment microscopy experiment. Therefore, we make predictions that our work should serve as a guide for future photodetachment microscopy experiments in time-dependent electric and magnetic fields.

scholarly journals Robust midgap states in band-inverted junctions under electric and magnetic fields

2018 ◽  
Vol 9 ◽  
pp. 1405-1413 ◽  
Author(s):  
Álvaro Díaz-Fernández ◽  
Natalia del Valle ◽  
Francisco Domínguez-Adame
Keyword(s):  
Magnetic Fields ◽  
Electric Field ◽  
Growth Direction ◽  
Band Model ◽  
Dirac Cone ◽  
Electron States ◽  
Heavy Atoms ◽  
Electric And Magnetic Fields ◽  
Band Inversion ◽  
Semiconductor Compounds

Several IV–VI semiconductor compounds made of heavy atoms, such as Pb1 −x Sn x Te, may undergo band-inversion at the L point of the Brillouin zone upon variation of their chemical composition. This inversion gives rise to topologically distinct phases, characterized by a change in a topological invariant. In the framework of the k·p theory, band-inversion can be viewed as a change of sign of the fundamental gap. A two-band model within the envelope-function approximation predicts the appearance of midgap interface states with Dirac cone dispersions in band-inverted junctions, namely, when the gap changes sign along the growth direction. We present a thorough study of these interface electron states in the presence of crossed electric and magnetic fields, the electric field being applied along the growth direction of a band-inverted junction. We show that the Dirac cone is robust and persists even if the fields are strong. In addition, we point out that Landau levels of electron states lying in the semiconductor bands can be tailored by the electric field. Tunable devices are thus likely to be realizable, exploiting the properties studied herein.

Quasi-static electric and magnetic fields in vacuum

2018 ◽  
Author(s):  
J. Pierrus
Keyword(s):  
Magnetic Field ◽  
Nineteenth Century ◽  
Magnetic Fields ◽  
Electric Field ◽  
Electromagnetic Induction ◽  
Point Of View ◽  
Time Dependent ◽  
Important Phenomenon ◽  
Electric And Magnetic Fields ◽  
Practical Standpoint

In this chapter, the transition from time-independent to time-dependent source densities and fields is made. It is here that Faraday’s famous nineteenth-century experiments on electromagnetic induction are first encountered. This important phenomenon—whereby a changing magnetic field produces an induced electric field (whose curl is now no longer zero)—forms the basis of most of the questions and solutions which follow. Some new and interesting examples—not usually found in other textbooks—are introduced. These are treated both from an analytical and numerical point of view. Also considered here is the standard yet important topic (at least from a practical standpoint) of mutual and self-inductance. Several questions deal with this concept.

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