External Quantizing Magnetic Field Research Articles

Electron power loss in metal-oxide nanostructures in quantizing magnetic field

Hot-electron power loss via electron interaction with bulk longitudinal polar optical phonon in metal-oxide two dimensional nanostructures in the presence of zero and finite quantizing magnetic fields is investigated using electron temperature model. The dependence of power loss in two-dimensional nanostructures of transparent conducting oxides like ZnO, SnO2, CdO, In2O3, Ga2O3 is presented as a function of electron temperature and carrier density in zero and finite magnetic fields. Numerical calculations establish that external quantizing magnetic field enhances power loss of electrons. Further, electron power loss is proportional to the electron temperature and varies inversely with the carrier density. The electron magneto-power loss qualitatively differs from the oscillating dependence of the electron-phonon scattering on the quantizing magnetic field.

The phenomenon of nonstationary nutation in the system of two-level quantum wells of a periodic superlattice with strong magnetic quantization

We investigate the superposition of nonstationary nutation processes that arose during the interaction of two-level systems of quantum wells of a superlattice with two exciting coherent optical pulses with various resonance detunings. According to the model under consideration, dipole transitions in two-level systems of quantum wells under the action of exciting pulses occur between the Landau levels of the main mini-band of the superlattice conduction band. This gives a direct opportunity to study the controlled variation of the course of optical nutation processes, by changing the intensity of an external quantizing magnetic field.

Electromagnetic and gravitational responses of two-dimensional noninteracting electrons in a background magnetic field

We compute electromagnetic, gravitational and mixed linear response functions of two- dimensional free fermions in external quantizing magnetic field at an integer filling factor. The results are presented in the form of the effective action and as an expansion of currents and stresses in wave-vectors and frequencies of the probing electromagnetic and metric fields. We identify the terms in linear response functions coming from geometric Chern-Simons, Wen-Zee, and gravitational Chern-Simons terms in effective action. We derive the expressions for Hall conductivity, Hall viscosity and find the current and charge density responses to the spatial curvature as well as stresses caused by inhomogeneous electromagnetic fields.

On the theory of the adsorption of atoms onto a metal surface in the presence of an external quantizing magnetic field

The Anderson-Newns model for the adsorption of atoms onto metals is generalized to the case of the presence of an external transverse quantizing magnetic field. Analytical expressions for the density of metal states in the external magnetic field are obtained. Analytical expressions for the density of adatom states are obtained in the approximation taking only the change in the density of substrate states into account. The charge exchange between the adatom and the metal is studied. The dependences of the density of adatom and transition-charge states on the magnetic field are studied for different values of the interaction constant. An analytical expression for the density of substrate states perturbed by adsorption is obtained.

Specific features of chemisorption on a size-quantized film in an external quantizing magnetic field

The energy of an electron of an adatom chemisorbed on a size-quantized film is investigated as a function of the external quantizing magnetic field. Consideration is given to the cases when the external magnetic field is directed parallel and transverse to the film surface. It is demonstrated that, as the magnetic field increases, the energy of chemisorption jumpwise decreases.

Nonlinear surface polaritons in 2D electron system in high magnetic field

The paper deals with the theoretical investigation of nonlinear surface polaritons (NSP) in isolated two-dimensional electron system (2DES) arranged at the interface between linear and nonlinear media and placed into the external quantizing magnetic field directed perpendicularly to 2DES. We consider that nonlinear medium dielectric permeability depends upon the tangential component of electric field only. It is shown that under the integer quantum Hall effect conditions all NSP characteristics are represented by the quantized values. It is found that the NSP spectrum contains two NSP modes - high-frequency and low-frequency ones. It is shown that the NSP can exist only in the case where the value of tangential component of electric field at the interface is less than a certain critical value. It is found that the resonant interaction between the NSP high-frequency mode and surface polariton mode occurs in the vicinity of the cyclotron resonance subharmonic.

Light absorption by impurity structures with quantum points in an external magnetic field

The light absorption by the quantum point - impurity center complex in an external quantizing magnetic field is studied in the effective mass approximation for the model of zero-radius potential. An expression for the absorption coefficient of light having longitudinal polarization by an impurity is derived when the influence of the magnetic field on the ground state of the impurity at the quantum point can be neglected. It is demonstrated that the edge of the absorption band of the impurity is shifted toward shorter wavelengths with increasing magnetic field strength. In this case, the absorption coefficient increases several times, which is interpreted as the effect of magnetic freezing-in of the ground state of the quantum point.

Electromagnetic waves in layered conductors and superlattices in a magnetic field

The collective electromagnetic wave excitations in layered conductors in an external quantizing magnetic field are studied theoretically. A set of coupled equations for the electric field components and the Green’s functions describing collective electromagnetic modes in such a system within the linear-response approach are obtained on the basis of a model of conducting planes embedded into a dielectric matrix. These equations, written in the layer-site representation, provide a basis for studies of the electromagnetic waves in the general case which does not imply either the spatial uniformity across the layers or the homogeneity within the conducting planes. The dispersion relations are obtained for the uniform and homogeneous layered conductors, which give a rich structure of collective electromagnetic modes in layered conductors in an external magnetic field. The dispersion and damping of helicons in layered conductors in the regimes of conventional and quantum Hall effects have been studied, both analytically and numerically. Two new modes propagating perpendicular to the magnetic field with frequencies of the order of the plasma frequency have been found.

Hot electrons under quantization conditions: I. Kinematics

A detailed analysis of the kinematic peculiarities of the interaction of bulk acoustic phonons with confined electrons in a quantum wire is peformed for intra- and inter-sub-band transitions. Due to quantization of the electron motion in a quasi-one-dimensional wire a new parameter appears in the kinetic theory ( is the electron effective mass, s is the sound velocity, is the quantum energy of the ground state and is some numerical constant which depends upon the shape of the quantizing potential), characterizing the electron - acoustic-phonon interaction. At low lattice temperatures , when , the intra-sub-band interaction has a strong inelastic character for the majority of electrons (assuming that the mean electron energy is also less than ). In the opposite case of high lattice temperatures, , this interaction is always quasi-elastic for the majority of electrons because the mean electron energy exceeds . Inter-sub-band scattering, on the other hand, is quasi-elastic at arbitrary lattice temperatures. These kinematic peculiarities of the electron - acoustic-phonon interaction are universal and, in general, do not depend on the physical nature of the quantizing field. It can be an external quantizing magnetic field or size-quantizing electrostatic potential, resulting in the confinement of electrons in a two-dimensional sheet or in a quantum wire, or confinement can be realized due to both electrostatic and magnetic potentials combined. The discussed peculiarities manifest themselves in novel kinetic properties of low-dimensional electron systems.

Inelastic electron-acoustic-phonon interaction in quantum-well wires

Due to the lack of transverse momentum conservation for the electron-acoustic-phonon interaction in quantum wires this interaction becomes strongly inelastic within a wide range of electron energies. As a result the electron distribution function has to be found from an integro-differential equation. We derive the new nonequilibrium distribution functions for these conditions and present the electric field dependences for the kinetic coefficients. Our approach can be applied as well for two-dimensional electron systems or for electrons subjected to an external quantizing magnetic field.

On a New Type of Dynamic Quantum Wells and Quantum Dots

AbstractElectron movement in a spatially periodic high‐frequency electric field is considered. If the spatial period is small enough and the frequency is sufficiently high, the effect of this field on the charge particle is in a sense equivalent to the effect of a time‐independent effective potential that is a sequence of deep ‘dynamic’ quantum wells where the electrons are confined. The physical model is proposed which could be described in terms of such a Hamiltonian. Also the influence of an external quantizing magnetic field on such quantum well is considered and the existence of a quantum dot in this system is demonstrated.

Possible beat effect of specific heat due to impurities in semi-metal in external magnetic field

The simple model of a single-band semi-metal or degenerate semiconductor with impurities in an external quantizing magnetic field is discussed. The susceptibility and specific heat are studied in their dependence on the field-induced quasi-local levels, due to the impurities. These levels are shown to cause additional oscillations in the thermodynamical quantities as functions of the magnetic field. Their contribution to the susceptibility and specific heat is comparable to the values for the undoped system if the impurity concentration c i fulfils the condition c i = (c e/4√π)( h ̷ ω/ε F) 3 2 , with c e the electron concentration.