Oscillatory effective mass in degenerate narrow-gap semiconductors in a quantizing magnetic field

An attempt is made to study the effect of a quantizing magnetic field on the effective electron mass in degeneraten-type narrow-gap semiconductors at low temperatures. It is found, takingn-Hg_1−x Cd _x Te as an example, that the effective electron mass shows an oscillatory magnetic-field dependence as is expected because of the dependence of the effective mass in degenerate non-parabolic bands on Fermi energy which oscillates with changing magnetic field. The amplitude of oscillations is, however, found to be significantly influenced by the alloy composition whereas the period is found to be independent of the band non-parabolicity, i.e. of the compositional parameter in ternary semiconductors.     

Magnetophonon oscillations of the differential susceptibility of semiconductors in a quantizing magnetic field

A Green's-function method is used to calculate the shape of the magnetophonon-oscillation line of the differential susceptibility of a semiconductor in a quantizing magnetic field. The amplitude of the resonant peak is shown to be proportional to g^2/3 (where g is the electron-phonon interaction constant), while the peak width is proportional to g^4/3.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 33–37, January, 1971.     

Righi-Leduc effect in a quantizing magnetic field

The Righi-Leduc effect in semiconductors with a Kane dispersion law in the presence of strong, quantizing, magnetic fields is studied theoretically. The explicit form of the dependence on the magnetic field, temperature, and concentration in arbitrary quantizing magnetic fields is established for semiconductors with a nondegenerate electron gas in the approximation of small nonparabolicity. A simple formula that is applicable for all strong magnetic fields, including quantizing fields, is derived for the Righi-Leduc coefficient in the case of strongly degenerate semiconductors with an arbitrary nonparabolic band. It is shown that in order to determine the photon part of the thermal conductivity ,ph directly from experiment it is best to employ samples with a nondegenerate electron gas in strong, but nonquantizing, magnetic fields.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 102–107, July, 1988.     

Brownian motion in a quantizing magnetic field

A model previously discussed by the author to study Brownian motion of charged carriers in a quantizing magnetic field is extended to include a Landau level-dependent friction parameter. A phase-space Fokker-Planck equation is used to derive a generalized diffusion equation describing spatial diffusion of the carriers, coupled with random jumps between adjacent Landau levels. This partial differential-difference equation is solved analytically. The longitudinal “global” diffusion coefficient is calculated and shown to be enhanced over the value in the extreme quantum limit.     

Effect of a quantizing magnetic field on the capacitance of MOS structures of small-gap semiconductors

An attempt is made to investigate the effect of a quantizing magnetic field on the capacitance of MOS structures of small-gap semiconductors havingn-channel inversion layers under the weak electric-field limit. It is found, takingn-channel InSb as an example, that both the MOS and surface capacitances show spiky oscillations with changing magnetic field. It is further observed that the sharpness and the depths of the spikes increase with increasing magnetic field whereas the depths are found to decrease with increasing thickness of the insulating layer. On leave of absence from the Department of Physics, Patna University, Patna, India     

Electrical conductivity of anisotropic semiconductors in quantizing magnetic fields

Scattering of a conduction electron with anisotropic mass upon a-shaped impurity potential in a homogeneous quantizing magnetic field is studied. An expression is obtained for the transverse electrical conductivity, on the basis of which the dependence of _yy on magnetic field direction is calculated for n-type Ge. The results obtained are analyzed.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 28–33, April, 1981.In conclusion, the author expresses his gratitude to A. G. Samoilovich and S. L. Korolyuk for their assistance in completing this study.     

Cold neutral plasma in a quantizing magnetic field

The chemical potential of a relativistic and an ultrarelativistic electron gas and the energy of an ultrarelativistic electron gas at T = 0 are expressed analytically as functions of the magnetic field. The possible application of these expressions to the investigation of super-compressed matter in the presence of superstrong magnetic fields is discussed.     

Thermo-emf of InSb in a transverse quantizing magnetic field

We have measured the thermo-emf of n-type indium antimonide in a transverse quantizing magnetic field. The results are explained using a theory that includes splitting of the Landau levels.Physics Institute of the Dagestanskii Center, Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 26–29, March, 1993.     

Influence of alloy composition on the dependence of the diffusivity-mobility ratio in ternary semiconductors on a quantizing magnetic field

An expression is derived for the diffusivity-mobility ratio in degenerate narrow-gap ternary semiconductors in the presence of a quantizing magnetic field. With the help of this expression, the diffusivity-mobility ratio is shown, taking n-Hg_1–xCd_xTe as an example, to have an oscillatory dependence on a quantizing magnetic field. The influence of alloy composition on such dependence is also investigated.     

Transient response of hot electrons in narrow-gap semiconductors at low temperatures in the presence of a longitudinal quantizing magnetic field

Transient response of hot electrons in narrow-gap semiconductors to a step electric field in the presence of a longitudinal quantizing magnetic field has been studied at low temperatures using displaced Maxwellian distribution. The energy and momentum balance equations are used assuming acoustic phonon scattering via deformation potential responsible for the energy relaxation and elastic acoustic phonon scattering together with ionized impurity scattering for momentum relaxation. The calculations for the variation of drift velocity and electron temperature as functions of time are made for n-Hg_0.8Cd_0.2 Te in the extreme quantum limit at 1.5 K and 4.2 K. The momentum and energy relaxation times are found to be of the same order of magnitudes as with the experimental values. The magnetic field and lattice temperature dependences of the relaxation rates have been investigated.One of the authors, Suchandra Bhaumik, acknowledges the Council of Scientific and Industrial Research (New Delhi) for financial support.     

Doped graphene in a quantizing magnetic field: Hall conductivity

The energy spectrum of electrons in doped graphene corresponding to the Landau levels in an external transverse magnetic field has been calculated in the low-energy approximation. The magnetic-field dependence of the electrical conductivity has been determined based on the derived dispersion relation of electrons in the doped graphene. The behavior of the conductivity has been analyzed for different impurity parameters, such as the hybridization potential and energy of adsorbed atoms.     

Inversion layer plasma waves in quantizing magnetic field

The electromagnetic plasma wave spectrum of an inversion layer plasma subject to Landau quantization is investigated here. Magnetic field effects on local and nonlocal plasma modes are determined using the two dimensional RPA magnetoconductivity tensor.     

Magnetic moment of a three-dimensional quantum well in a quantizing magnetic field

The magnetic moment of an electron gas in a three-dimensional quantum well is studied. It is shown that two kinds of oscillations arise: oscillations caused by a change of the magnetic field strength and those caused by a change in the field direction.     

Some properties of an electron gas in a quantizing magnetic field

The electron gas neutralized by a rigid positive background and in a quantizing magnetic field, is studied in a ‘quasi-classical’ model previously proposed by the author and collaborators. The plasma oscillation of the electron gas shows an acoustic-type dispersion for small wave vector. The potential behind an ion moving along the direction of the magnetic field is calculated and is found to have a sinusoidal behaviour. Some consequences of this potential are pointed out. The energy loss by a moving charge in the electron gas is shown to exhibit some interesting properties. Other quantities such as light scattering and magneto-acoustic oscillations are also discussed. A derivation is given for a ‘quasi-classical’ linear response in the finite relaxation time approximation.     

Interband resonant tunneling in superconductor heterostructures in a quantizing magnetic field

The resonant tunneling of electrons through quasistationary levels in the valence band of a quantum well in double-barrier structures based on III–V materials with type-II heterojunctions is considered in a quantizing magnetic field directed perpendicularly to the interfaces. The transmission coefficients of the tunnel structure for transitions from states corresponding to different Landau levels are calculated using the Kane model. It is shown that transitions with a unit change in the Landau level index n as a result of mixing of the wave functions of states with opposite spin orientations are possible on the interfaces due to spin-orbit coupling. The probability of such transitions can be comparable to the probability of transitions without a change in the Landau level index for InAs/AlGaSb/GaSb resonant-tunneling structures. Fiz. Tverd. Tela (St. Petersburg) 40, 2121–2126 (November 1998)     

Theoretical analysis of the gate capacitance inn-channel inversion layers on ternary chalcopyrite semiconductors in the presence of a quantizing magnetic field

An attempt is made to study theoretically, the dependence of the gate capacitance inn-channel inversion larges on ternary chalcopyrite semiconductors on a quantizing magnetic field, takingn-channel inversion layers on CdGeAs₂ as an example. It is found, on the basis of a newly derived electron energy spectrum of the above class of semiconductors, that the gate capacitance exhibits spiky oscillations with changing magnetic field and the oscillatory behaviour is in qualitative agreement with the experimental observation reported in the literature for the MOS structure of Hg_1–x Cd _x Te.     

Degenerate Fermi gas of charged particles in a quantizing magnetic field

The strength at which a magnetic field has a quantizing effect on the particles of a degenerate ultrarelativistic electron gas is essentially the same as that for a nonrelativistic proton gas of the same density. Discrete field strengths at which the chemical potentials of these gases have fixed values are expressed in terms of the same index of the Landau quantum level.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 5–9, September, 1991.