42 research outputs found
Magneto-Gyrotropic Photogalvanic Effects in Semiconductor Quantum Wells
We show that free-carrier (Drude) absorption of both polarized and
unpolarized terahertz radiation in quantum well (QW) structures causes an
electric photocurrent in the presence of an in-plane magnetic field.
Experimental and theoretical analysis evidences that the observed photocurrents
are spin-dependent and related to the gyrotropy of the QWs. Microscopic models
for the photogalvanic effects in QWs based on asymmetry of photoexcitation and
relaxation processes are proposed. In most of the investigated structures the
observed magneto-induced photocurrents are caused by spin-dependent relaxation
of non-equilibrium carriers
Behavior of Dynamical Systems in the Regime of Transient Chaos
The transient chaos regime in a two-dimensional system with discrete time
(Eno map) is considered. It is demonstrated that a time series corresponding to
this regime differs from a chaotic series constructed for close values of the
control parameters by the presence of "nonregular" regions, the number of which
increases with the critical parameter. A possible mechanism of this effect is
discussed.Comment: 4 pages, 2 figure
The Influence of Voltage Polarity on the Regime of Atmospheric-Pressure Glow Discharge Operation in Flows of Atomic and Molecular Gases
Effect of heat on the nonlinearity of plane strontium titanate film capacitors on sapphire in a microwave field
Interleukin-1 bedingte Endothelzellaktivierung als Invasionsfaktor beim Urothelkarzinom der Harnblase
X-ray diffraction has been used to elucidate the structure and phase behavior of several liquid-crystalline dendrimers with a different surface topology of the terminal chains. This includes second-generation liquid-crystalline block and statistical dendrimers with mixed aliphatic and mesogenic terminal groups as well as homo-dendrimers of several generations containing only mesogenic end groups. The homo-dendrimers of generation one to four display a monolayer smectic phase, while the fifth generation shows a more ordered columnar phase. The block-dendrimer of the second generation has a bilayer smectic phase. The precise structure of the lamellar ordering has been determined by X-ray reflectivity from thin films on a substrate. The second-generation statistical dendrimer does not show any mesogenic phase. The observed phase behavior is discussed in terms of the frustration due to competition between the stiff geometry of the dendritic matrix and the close-packing conditions of the terminal chains