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