3,814 research outputs found
Numerical Investigation on Asymmetric Bilayer System at Integer Filling Factor
Deformation of the easy-axis ferromagnetic state in asymmetric bilayer
systems are investigated numerically. Using the exact diagonalization the
easy-axis to easy-plane ferromagnetic transition at total filling factor 3 or 4
is investigated. At still higher filling, novel stripe state in which stripes
are aligned in the vertical direction occurs. The Hartree-Fock energies of
relevant ordered states are calculated and compared.Comment: 4 pages, 6 figures, Proceedings of EP2DS-15, to appear in Physica
Capacitance of a Double-Heterojunction GaAs/AlGaAs Structure Subjected to In-Plane Magnetic Fields: Results of Self-Consistent Calculations
The capacitance of a double-heterojunction structure with a wide GaAs undoped
layer embedded between two selectively doped AlGaAs barriers is calculated
self-consistently as a function of intensity of the in-plane magnetic field.
With increasing field intensity the capacitance initially increases and after
reaching a maximum decreases toward a high field limit which is less than its
zero field value. This behaviour is attributed to 'breathing', or charge
redistribution, of the 2D electron gas at individual heterojunctions due to a
combination of the confining potential and the magnetic field.Comment: LaTeX, 9 pages, 7 figs. available on request from [email protected] in 1
PS file (compressed and uuencoded
Capacitance of Gated GaAs/AlGaAs Heterostructures Subject to In-plane Magnetic Fields
A detailed analysis of the capacitance of gated GaAs/AlGaAs heterostructures
is presented. The nonlinear dependence of the capacitance on the gate voltage
and in-plane magnetic field is discussed together with the capacitance quantum
steps connected with a population of higher 2D gas subbands. The results of
full self-consistent numerical calculations are compared to recent experimental
data.Comment: 4 pages, Revtex. 4 PostScript figures in an uuencoded compressed file
available upon request. Phys. Rev.B, in pres
Breast Self-Examination Teaching for Women in Chemical Dependency Programs
Fifty-two women from 5 chemical dependency programs participated in a 1 hour health education program teaching breast self-examination using breast models. Tactile skills and general information about breast cancer and breast self-examination were presented. The program was evaluated for its ability to teach this high risk population. Nine true/false questions and lump detection skills were evaluated using_a pretest/posttest non-experimental design. A level of significance for the true/false questions was set at .01, and for lump detection skills it was set at .05. Dependent t tests was used to statistically analyze the data. Participants improved their general knowledge about breast cancer and self-examination as a result of this program (p \u3c.01). Lump detection skills also improved (p \u3c.05). This study indicates health education programs are of value and can potentially decrease the survival discrepancy for breast cancer for a specific high risk population
Resistance spikes and domain wall loops in Ising quantum Hall ferromagnets
We explain the recent observation of resistance spikes and hysteretic
transport properties in Ising quantum Hall ferromagnets in terms of the unique
physics of their domain walls. Self-consistent RPA/Hartree-Fock theory is
applied to microscopically determine properties of the ground state and
domain-wall excitations. In these systems domain wall loops support
one-dimensional electron systems with an effective mass comparable to the bare
electron mass and may carry charge. Our theory is able to account
quantitatively for the experimental Ising critical temperature and to explain
characteristics of the resistive hysteresis loops.Comment: 4 pages, 3 figure
Novel critical field in magneto-resistance oscillation of 2DEG in asymmetric GaAs/AlGaAs double wells measured as a function of the in-plane magnetic field
We have investigated the magnetoresistance of strongly asymmetric double-well
structures formed by a thin AlGaAs barrier grown far from the interface in the
GaAs buffer of standard heterostructures. In magnetic fields oriented parallel
to the electron layers, the magnetoresistance exhibits an oscillation
associated with the depopulation of the higher occupied subband and with the
field-induced transition into a decoupled bilayer. In addition, the increasing
field transfers electrons from the triangular to rectangular well and, at high
enough field value, the triangular well is emptied. Consequently, the
electronic system becomes a single layer which leads to a sharp step in the
density of electron states and to an additional minimum in the
magnetoresistance curve.Comment: 3 pages, 3 figure
Circuit model for spin-bottleneck resistance in magnetic-tunnel-junction devices
Spin-bottlenecks are created in magnetic-tunnel-junction devices by spatial
inhomogeneity in the relative resistances for up and down spins. We propose a
simple electrical circuit model for these devices which incorporates
spin-bottleneck effects and can be used to calculate their overall resistance
and magnetoresistance. The model permits a simple understanding of the
dependence of device magnetoresistance on spin diffusion lengths, tunneling
magnetoresistance, and majority and minority spin resistivities in the
ferromagnetic electrodes. The circuit model is in a good quantitative agreement
with detailed transport calculations.Comment: 4 pages, 3 figures, submitted to Phys. Rev.
- …