Spin Relaxation in a Quantized Hall Regime in Presence of a Disorder

We study the spin relaxation (SR) of a two-dimensional electron gas (2DEG) in the quantized Hall regime and discuss the role of spatial inhomogeneity effects on the relaxation. The results are obtained for small filling factors ($\nu\ll 1$) or when the filling factor is close to an integer. In either case SR times are essentially determined by a smooth random potential. For small $\nu$ we predict a "magneto-confinement" resonance manifested in the enhancement of the SR rate when the Zeeman energy is close to the spacing of confinement sublevels in the low-energy wing of the disorder-broadened Landau level. In the resonant region the $B$-dependence of the SR time has a peculiar non-monotonic shape. If $\nu\simeq 2n+1$, the SR is going non-exponentially. Under typical conditions the calculated SR times range from $10^{-8}$ to $10^{-6}$s.Comment: 10 pages, 1 figure. To appear in JETP Letter

Spin relaxation in a two-electron quantum dot

We discuss the rate of relaxation of the total spin in the two-electron droplet in the vicinity of the magnetic field driven singlet-triplet transition. The total spin relaxation is attributed to spin-orbit and electron-phonon interactions. The relaxation process is found to depend on the spin of ground and excited states. This asymmetry is used to explain puzzles in recent high source-drain transport experiments.Comment: 9 pages in the PDF format, 1 figur

Effect of Electron Energy Distribution Function on Power Deposition and Plasma Density in an Inductively Coupled Discharge at Very Low Pressures

A self-consistent 1-D model was developed to study the effect of the electron energy distribution function (EEDF) on power deposition and plasma density profiles in a planar inductively coupled plasma (ICP) in the non-local regime (pressure < 10 mTorr). The model consisted of three modules: (1) an electron energy distribution function (EEDF) module to compute the non-Maxwellian EEDF, (2) a non-local electron kinetics module to predict the non-local electron conductivity, RF current, electric field and power deposition profiles in the non-uniform plasma, and (3) a heavy species transport module to solve for the ion density and velocity profiles as well as the metastable density. Results using the non-Maxwellian EEDF model were compared with predictions using a Maxwellian EEDF, under otherwise identical conditions. The RF electric field, current, and power deposition profiles were different, especially at 1mTorr, for which the electron effective mean free path was larger than the skin depth. The plasma density predicted by the Maxwellian EEDF was up to 93% larger for the conditions examined. Thus, the non-Maxwellian EEDF must be accounted for in modeling ICPs at very low pressures.Comment: 19 pages submitted to Plasma Sources Sci. Techno

The significance of Goodpasture antigen in hereditary nephritis

INTRODUCTION: Two types of hereditary nephritis, nonprogressive and progressive, clinically present as asymptomatic haematuria, sometimes combined with proteinuria. At the onset, in both types, light microscopic changes are minimal, immunofluorescence findings are negative, and diagnosis can be made only upon electron microscopic findings that are considered to be specific. OBJECTIVE: The aim of this study was to determine the significance of Goodpasture antigen detection in diagnosis of progressive and nonprogressive hereditary nephritis in its early phase. METHOD: Analysis of renal biopsy specimens was done in patients with hereditary nephritis that were followed from 1990 to 2005. Progression of renal disease was examined in 14 patients with Alport's syndrome, 10 patients with thin basement membrane disease, and 6 patients with unclassified hereditary nephritis diagnosed. For all these cases, indirect immunofluorescence study with serum from a patient with high titer of Goodpasture autoantibodies that recognize the antigenic determinants in human glomerular and tubular basement membrane was performed. RESULTS: In 11 out of 14 cases diagnosed as Alport's syndrome, there was negative staining with Goodpasture serum, and in 3 additional cases with Alport's syndrome, expression of Goodpasture antigen in glomerular basement membrane and thin basement membrane was highly reduced. In all 10 patients with thin basement membrane disease, immunofluorescence showed intensive, bright linear staining with Goodpasture serum along glomerular and tubular basement membrane. In 2 out of 6 patients with unclassified hereditary nephritis, Goodpasture antigen expression was very strong, in one patient it was very reduced, and in 3 patients it was negative. CONCLUSION: The results of our study show that Goodpasture antigen detection plays a very important role in differential diagnosis of progressive and nonpregressive hereditary nephritis, particularly in early phases of the disease

Landau damping and anomalous skin effect in low-pressure gas discharges: Self-consistent treatment of collisionless heating

In low-pressure discharges, where the electron mean free path is larger or comparable with the discharge length, the electron dynamics is essentially nonlocal. Moreover, the electron energy distribution function (EEDF) deviates considerably from a Maxwellian. Therefore, an accurate kinetic description of the low-pressure discharges requires knowledge of the nonlocal conductivity operator and calculation of the non-Maxwellian EEDF. The previous treatments made use of simplifying assumptions: a uniform density profile and a Maxwellian EEDF. In the present study a self-consistent system of equations for the kinetic description of nonlocal, nonuniform, nearly collisionless plasmas of low-pressure discharges is reported. It consists of the nonlocal conductivity operator and the averaged kinetic equation for calculation of the non-Maxwellian EEDF. This system was applied to the calculation of collisionless heating in capacitively and inductively coupled plasmas. In particular, the importance of accounting for the nonuniform plasma density profile for computing the current density profile and the EEDF is demonstrated. The enhancement of collisionless heating due to the bounce resonance between the electron motion in the potential well and the external radio-frequency electric field is investigated. It is shown that a nonlinear and self-consistent treatment is necessary for the correct description of collisionless heating