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The hot-electron magnetotransport of epitaxial Fe/Au/Fe/GaAs(001) spin-valves is investigated by ballistic-electron magnetic microscopy. A magnetocurrent amplitude larger than 500% is observed at room temperature close to the Schottky barrier energy. Remarkably, this magnetocurrent is not significantly affected by the thickness reduction of ferromagnetic films, down to 5 atomic layers of the Fe(001) top electrode. This rather suggests a dominant interfacial spin-filtering effect. Finally, the magnetocurrent is strongly reduced when the effective mass of the semiconductor collector is increased. These observations are consistent with recent theoretical prediction of k-space spin-filtering effect in epitaxial spin-valves attached to a semiconducting lead. [ABSTRACT FROM AUTHOR]

This paper presents a predictive Keldysh nonequilibrium many body Green’s functions theory for quantum transport including high order electron-electron, electron-phonon, electron-impurity, and interface roughness scattering processes. Our approach is fully frequency and momentum dependent including nondiagonal dephasing terms in both frequency and k-space. A detailed balance between coherent and scattering processes leads to local current conservation even if a small number of states is considered. Good agreement with experiments is obtained for a terahertz quantum cascade laser. [ABSTRACT FROM AUTHOR]

We demonstrate how two optical functionalities can be implemented in a single photonic crystal structure by carefully engineering dispersion in several different bands at several different wavelengths. We use the concept for optically pumped dye doped hybrid polymer band edge lasers and show how a rectangular photonic crystal lattice imprinted into the surface can provide both feedback for in-plane band edge lasing and couple pump light into the device plane, thus increasing the emitted intensity and lowering the lasing threshold by more than an order of magnitude. [ABSTRACT FROM AUTHOR]

Examines the magnetic focusing in two-dimensional hole systems. Demonstration of ballistic hole transport; Measurement of the constant energy contours in k-space; Emergence of a more complicated band structure for triangular wells.

We apply the principle of structured illumination microscopy to a fluidic imaging device. The necessary phase shifts are no longer obtained by controlled displacement of the illumination pattern but by flowing the sample itself. The resulting scheme retains all the benefits of fluid systems while enabling easy integration with existing microscopes, flow cytometers, and aquatic imagers. We present the theory of flow-based structured illumination and demonstrate the technique experimentally by reconstructing super-resolved images of yeast cells. [ABSTRACT FROM AUTHOR]

Strong light-matter coupling is demonstrated in monolithic microcavities with only three ZnSe quantum wells embedded. Basis for this observation is the excellent structural quality of the sample as confirmed by scanning transmission electron microscopy measurements. A comparative large energy splitting between the upper and lower polariton (LP) of about 19 meV is observed by reflectivity measurements in real and k-space. Efficient polariton relaxation is shown by photoluminescence measurements at low temperatures in k-space. These beneficial properties of the sample result in a nonlinear increase of the lower polariton population in excitation density dependent measurements before the photonic cavity emission becomes dominant. [ABSTRACT FROM AUTHOR]