Mesude Saglam

Two-electron singlet states in semiconductor quantum dots with Gaussian confinement: a single-parameter variational calculation

The problem of two electrons in a three-dimensional quantum dot with Gaussian confinement is investigated for the singlet pairing by a variational method with a very simple wavefunction containing only a single parameter and a Jastrow-like factor, which is shown to yield fairly good results for deep confining potentials. The calculation is also performed for a few realistic semiconductor quantum dots and the phase diagrams for the two-electron singlet states are obtained for these materials. The pair density function is calculated for several parameter values and its peak positions are obtained as a function of the confinement length and the depth of the potential to study the behaviour of the electron-pair size. The size of the bound pair of electrons is also obtained by directly calculating the average distance between the two electrons in three different ways and compared with the pair correlation results. It is furthermore shown that, other properties remaining the same, the two-electron energy and the electron-pair size depend crucially on the effective electronic mass and the dielectric constant of the material. Finally, the ways of improving the wavefunction are also indicated.

CALCULATION OF THE FLUX ASSOCIATED WITH THE ELECTRON'S SPIN ON THE BASIS OF THE MAGNETIC TOP MODEL

The flux associated with the electrons spin is calculated on a the basis of the magnetic top (spherical top) model which can be made equivalent to a circular current loop with radius R in x–y plane in the presence of a uniform magnetic field in z-direction. It is found that the flux associated with the electrons spin is exactly equal to +Φ0/2 for a spin down electron and -Φ0/2 spin up one.

On the metric of a non-Hermitian model

We introduce a new, exactly solvable non-Hermitian model with real spectrum, and derive a formula for the metric operator in the Hilbert space, which relates the problem to a Hermitian one.

Quantized magnetic flux through the excited-state orbit of the hydrogen atom

We have investigated the spin-dependent quantized magnetic fluxes through the ground-state electronic orbit of the hydrogen atom. We show that the corresponding fluxes are (1/2)Φ0 for the spin-up case and (3/2)Φ 0 for the spin-down case, respectively, where Φ0 = hc/e is the flux quantum. Using the energy-flux proportionality, we also show that the spin-up case (where the electron spin is antiparallel to the proton spin, resulting in zero total spin) is the spin-dependent ground state of the hydrogen atom. The present result helps to understand the spin flip-flop in excitonic transitions in nanostructures.

Calculation of the magnetic moment of the photon

we calculate the magnetic moment of each gamma photon created as a result of the electron-positron annihilation. We find that, the z-component of the magnetic moment is equal to ±(ec / ω) (where ω is the angular frequency of the gamma photons). We then argue that any photon with an angular frequency ω should carry a magnetic moment of ±(ec / ω) along the propagation direction. Here the (+) and (−) signs stand for the right and left hand circular helicity respectively.

Flux quantization associated with electron spin for correlated electron system in QHE

Abstract We calculate the magnetic flux associated with the electrons spin for correlated electron system in quantum Hall effect. We show that the spin contribution to the magnetic flux is g ∗ Φ 0 /4 for a spin down electron and −g ∗ Φ 0 /4 for spin up one. Where Φ 0 =hc/e is the flux quantum and g ∗ is the effective Lande-g factor of the correlated electron system.

Surface magnetostatic waves and magnetic polaritons at the junction of the magnetic superlattice and magnetic material

Abstract Using electromagnetic wave theory in the Voigt configuration, the surface magnetostatic waves (MW) and magnetic polaritons localized at the junction between semi-infinite magnetic superlattice (SL) and magnetic material are analysed theoretically. The general dispersion relation for localized MW and magnetic polaritons are derived by the transfer matrix method in the long-wavelength limit. Some examples of the wave spectra are presented for SL composed of two magnetic materials (Fe/Co). The dispersion curves for different contact materials (contact material with Ni, Co and Gd, respectively) are calculated numerically and the ranges within which surface modes frequencies lie are discussed.

Quantized magnetic flux through the electronic orbits of dirac hydrogen atom and its relation with the spin dependent selection rules and photons intrinsic flux

We have calculated the changes in the quantized magnetic fluxes corresponding to the electronic orbits of Dirac hydrogen atom within the framework of Dirac theory and found that the flux change between the final state and the initial state is equal to (±Φ0 or zero).We have also calculated the non-zero matrix elements for dipole transitions (such as 1s↔2p and 2p↔3d) for the solutions of Dirac hydrogen atom. We find a complete agreement among all the above results. The combined result is that photon should carry an intrinsic flux quantum of (Φ0=hc/e).

Hopping conduction in amorphous superlattices

The effect of the intra-well hopping associated with an asymmetric interface charge distribution on the general hopping conductivity in amorphous superlattices is studied. It is found that the current density and hence the conductivity will be larger compared to that of an ordinary superlattice.