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1
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Cyclotron Frequencies and Quanta of the Landau Levels in Semiconductors Having Ellipsoidal Fermi Surfaces Studied in Dependence on Direction of the Magnetic Field

100%
Olszewski S., Roliński T.
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vol. 126
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issue 6
1304-1311
EN
A method of calculating the Landau levels in crystals having the ellipsoidal Fermi surfaces has been presented with an accent put on the directional dependence of the energy quanta defined by the levels. Physically the problem concerns mainly semiconductors examined in a nearly-free electron approximation. In this case the shape of the Fermi surface is defined by three different effective masses entering the electron Hamiltonian. Beyond of the masses the method, which can be applied for an arbitrary direction of the magnetic field, does contain no empirical parameters in its framework.
2
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Simple Method for Calculating the Weak-Field Electron Diamagnetism in Cubic Lattices

80%
Olszewski S.
Acta Physica Polonica A
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2002
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vol. 101
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issue 2
249-265
EN
The idea of electron wave packets moving along closed anisotropic Fermi surfaces placed in a constant magnetic field has been applied to the calculation of the orbital magnetic moment of an individual free electron and tightly-bound s-electron in a crystal lattice. In each case the magnetic moment is obtained as a derivative of the electron energy done with respect to the strength of the magnetic field. In the next step, calculations have been extended to electron ensembles. For a free-electron ensemble a thorough calculation of the weak-field magnetic moment gives a result similar to that obtained by a well-known method developed by Landau. On the other hand, calculations done for the s-band of the tightly-bound electrons of metallic iron give an absolute value of the magnetic moment much smaller than in the free-electron case. Simultaneously, the sign of the moment is changed indicating a lowering of the iron band electron energy with magnetization.
3
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Magnetotransport and Magnetooptics of InAs_{1-x}Sb_{x} and Heterojunctions Combinations Formed Between InAs and GaSb, AlSb Or InAs_{1 -x}Sb_{x}

80%
Stradling R.
Acta Physica Polonica A
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1997
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vol. 92
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issue 5
851-865
EN
Cyclotron resonance and interband measurements are reported in magnetic fields up to 160 T for InAs/InAs_{1-x}Sb_{x} superlattices, one of which is a "self-organised" or "natural" superlattice, and InAs_{1-x}Sb_{x} epilayers. The samples were grown by MBE at temperatures between 370°C to 500°C. No dependence of the band gap, effective masses or g-values on the growth temperature was detected. Anomalous tilt behaviour was observed for the superlattices. Inversion asymmetry induced spin-splitting of the subbands in gated InAs quantum wells is investigated by means of the Shubnikov-de Haas effect and cyclotron resonance. The non-parabolicity was well fitted by Kane theory, although the measured values of effective mass were substantially higher than predictions. Infrared life time measurements at wavelengths between 6 and 85 microns are undertaken with free electron lasers on InAs/InAs_{1-x}Sb_{x} superlattices and InAs/AlSb quantum wells. Suppression of the Auger recombination times is demonstrated with the superlattices.
4
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Optical Detection of Cyclotron Resonance in Serpentine Superlattice Quantum-Wire Arrays

80%
Świątek K., Weman H., Miller M., Petroff P., Merz J.
Acta Physica Polonica A
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1993
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vol. 84
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issue 3
583-586
EN
We report low-temperature studies of microwave-induced cyclotron resonance of photo-generated carriers in (Al,Ga)As serpentine superlattice quantum-wire arrays. The geometric size of the parabolic-crescent cross-section of the quantum wires was of the order of 100 Å × 50 Å, depending on the angle of the vicinal substrate and the amount of parabolic curvature. Comparing the obtained spectra, we estimate the relative degree of carrier confinement in the ordered AlGaAs structure.
5
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Detection of Single Submillimeter-Wave Photons Using Quantum Dots

80%
Komiyama S., Astafiev O., Antonov V., Kutsuwa T.
Acta Physica Polonica A
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2000
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vol. 98
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issue 3
271-278
EN
Single-photon detection in a range of submillimeter waves (λ = 0.17-0.20 mm) is demonstrated by using lateral semiconductor quantum dots fabricated on a high-mobility GaAs/AlGaAs single heterostructure crystal. When a submillimeter photon is absorbed by the quantum dot while it is operated as a single-electron transistor, it switches on (or off) the conductance through the quantum dot. An incident flux of 0.1 photons/s on an effective detector area, (0.1 mm)^{2}, is detected with a 1 ms time resolution. The effective noise equivalent power is roughly estimated to reach on the order of 10^{-22} W/Hz^{1/2}, a value superior to the ever reported best values of conventional detectors by a factor more than 10^{4}.
6
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Time-Resolved Microwave Spectroscopy of High Electron Mobility GaAs/AlGaAs Structures

80%
Khachepuridze A., Ivanov V., Godlewski M., Regiński K., Bugajski M.
Acta Physica Polonica A
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1998
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vol. 94
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issue 3
387-391
EN
Mechanism of the optical detection of cyclotron resonance via emission from 2D electron gas in modulation doped quantum wells and in high electron mobility structures of GaAs/AlGaAs is discussed based on the results of time-resolved optical detection of cyclotron resonance. An important role of impact ionization processes is demonstrated. We also show that microwave radiation destroys emission enhancement at the Fermi level and the relevant mechanism is proposed.
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