24 research outputs found
Magnetic Field Induced Spin Polarization of AlAs Two-dimensional Electrons
Two-dimensional (2D) electrons in an in-plane magnetic field become fully
spin polarized above a field B_P, which we can determine from the in-plane
magnetoresistance. We perform such measurements in modulation-doped AlAs
electron systems, and find that the field B_P increases approximately linearly
with 2D electron density. These results imply that the product |g*|m*, where g*
is the effective g-factor and m* the effective mass, is a constant essentially
independent of density. While the deduced |g*|m* is enhanced relative to its
band value by a factor of ~ 4, we see no indication of its divergence as 2D
density approaches zero. These observations are at odds with results obtained
in Si-MOSFETs, but qualitatively confirm spin polarization studies of 2D GaAs
carriers.Comment: 4 pages, 5 figure
Entangled Photons from Small Quantum Dots
We discuss level schemes of small quantum-dot turnstiles and their
applicability in the production of entanglement in two-photon emission. Due to
the large energy splitting of the single-electron levels, only one single
electron level and one single hole level can be made resonant with the levels
in the conduction band and valence band. This results in a model with nine
distinct levels, which are split by the Coulomb interactions. We show that the
optical selection rules are different for flat and tall cylindrically symmetric
dots, and how this affects the quality of the entanglement generated in the
decay of the biexciton state. The effect of charge carrier tunneling and of a
resonant cavity is included in the model.Comment: 10 pages, 8 figure
Exciton Spin Dynamics in Semiconductor Quantum Wells
In this paper we will review Exciton Spin Dynamics in Semiconductor Quantum
Wells. The spin properties of excitons in nanostructures are determined by
their fine structure. We will mainly focus in this review on GaAs and InGaAs
quantum wells which are model systems.Comment: 55 pages, 27 figure
Scanning tunneling microscope for magneto-optical imaging
Contains fulltext :
28002___.PDF (publisher's version ) (Open Access
Magneto-optical Faraday effect probed in a scanning tunneling microscope
Semiconductor tips are used as local photodetectors in a scanning tunneling microscope. We demonstrate that this configuration is sensitive to small light intensity variations, as supported by a simple model. The principle is applied to the detection of Faraday ellipticity of a Pt/Co multilayer sample. The outlook of this new technique in magneto-optical imaging is briefly discussed
Antiparallel and perpendicular magnetization alignment for Co / Ru multilayers
Several Co / Ru multilayers were grown in which the magnetization directions of consecutive Co layers were aligned antiparallel and along the film normal. The magnetization curves for these multilayers agree with the curves obtained by minimizing the total energy including anisotropy and interlayer coupling. These multilayers were part of a series with Co thicknesses of 11 and 22 Å and Ru thicknesses varying between 5 and 20 Å. Torque and magnetization measurements showed that the multilayers with 11 Å Co had a perpendicular easy axis while for the 22 Å Co series an in-plane preferential orientation was observed. A strong antiferromagnetic interlayer coupling was obtained for Ru thicknesses of about 8 Å