Nanopatterning Optimization of Zinc Phosphide: Hole Mobility up to 560 cm2/Vs with Selective Area Epitaxy

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We study the effect of a magnetic field (applied along the c axis) on the low-energy, incommensurate magnetic fluctuations in superconducting La1.82Sr0.18CuO4. The incommensurate peaks at 9 meV, which in zero field were previously shown to sharpen in q on cooling below T-c [T. E. Mason , Phys. Rev. Lett. 77, 1604 (1996)], are found to broaden in q when a field of 10 T is applied. The applied field also causes scattered intensity to shift into the spin gap. We point out that the response at 9 meV, though occ

We study the dynamic motion of magnetic structures composed of micron-size ferromagnetic particles. The supraparticle structures are retained in a microfluidic channel by a local oscillating magnetic field while subjected to a viscous liquid flow. We analyze the position of the magnetic structures as a function of the flow velocity and of the frequency and amplitude of the magnetic field. We also study the conditions for release of the magnetic structures from the localized magnetic field region.

We present an exact model for determining the cogging torque in a brushless DC (BLDC) motor. It is based on the conformal mapping (CM) method, by which the motor configuration is transformed to a configuration where the magnetic field can be determined. Then, by integrating the field over the stator surface, the cogging torque is determined. By varying some motor parameters, which is easy to do, an optimal configuration with the minimal cogging torque is obtained. We have confirmed the results by the finite

We develop a dynamical theory for the optical injection of charge and spin current originating from the interferences between two coherent laser pulses of frequencies omega and 2omega. Multiband Bloch equations which include one- and two-photon interband transitions are derived. They also account for ac Stark shifts and intersubband two-photon transitions. The model is used to describe the case of time-dependent charge and spin current injection in a symmetric GaAs/AlGaAs quantum well. A comparison to the b

Using the SULTAN test facility the d.c. behaviour of three subsize NbTi cable-in-conduit (CIC) conductors has been studied. The d.c. performance of the cables is compared with the critical currents and the current sharing temperatures expected from the strand data. As a basis for this comparison the critical current of the NbTi strands has been measured in the temperature range of 4.2-6.5 K in magnetic fields of up to 7.5 T. The d.c. performance of the NbTi subsize conductors has been found to be not signif

The present work is devoted to the study of the dynamics of multi-photon processes in semiconductor heterostructures. A time-dependent description is important for understanding in detail the transient response of semiconductors excited by ultrashort optical pulses. In the first part of this thesis, we set up a phenomenological model based on rate equations, in order to investigate the possibility of measuring degenerate two-photon gain in a semiconductor microcavity. The amplification predicted by the mode

Planar magnetic sensor, made in particular via CMOS techniques on a semiconductor substrate (1) of for example parallelepiped shape. It includes an amorphous ferromagnetic core (10) in the shape of a Greek cross which occupies the two diagonals of the square defined by the outer contour (90) of the excitation coil (9), the latter being made in the form of a planar winding of square shape. One thus measures, via flat detection coils (70, 80 and 71, 81) which are mounted in series and in a differential arrang

In certain power applications, Bi-2223 conductors carrying AC current will be subjected to external magnetic fields, whose orientation and conductor’s geometry are of major significance for the AC loss magnitude. This paper investigates the influence of the geometry and aspect ratio of non-twisted Bi-2223 conductors in reducing the AC loss for such applications. A numerical model of high-Tc materials has been used in FEM simulations. The model incorporates power-law E-J characteristics with Jc defined by bo

Experimental data characterizing indoor electric and magnetic fields radiated by power line communication (PLC) systems and used for the calculation of a local transfer function (coupling factor) are presented. It is shown that the indirect determination of electric field using magnetic field measurements and assuming a plane wave approximation may result in an underestimation of the electric field. Additionally, it is shown that the radiated field magnitudes vary significantly as a function of the position

We demonstrate edge-emitting lasers based on self-assembled InAs quantum dots (QDs) on GaAs substrates. The InAs QDs are embedded in an InGaAs quantum well (QW) to red-shift the lasing transition. The lasers emit at lambda=1.2 mum with threshold current densities approximate to100 A/cm(2). Maximum modal gains on the order of 5 cm(-1) are deduced for a single QD sheet.

Transient photocurrents are investigated in ferroelectric lead zirconate titanate (PZT) films illuminated by laser pulses in the spectral range of 340-380 nm. At low electric fields, the photocurrent is sensitive to the ferroelectric polarization state and changes sign upon the polarization switching. At higher fields, the polarization-independent current proportional to the applied electric field is dominant. The spectral dependence of polarization-dependent current is controlled by the excitation of charg

By using chemical beam epitaxy at growth temperatures as low as 460-480 degrees C, we have overcome strain relaxation problems that prevented so far the successful use of InAsP quantum wells in 1.55 mu m lasers. Five quantum well InAsP/InGaAsP horizontal cavity lasers showed 88% internal efficiency, 1.6 cm(-1) losses per well, and 33 A/cm(2) transparency current density per well, which equal or even surpass the best published characteristics for 1.55 mu m wavelength lasers based on any material system. More

Nanopatterning Optimization of Zinc Phosphide: Hole Mobility up to 560 cm2/Vs with Selective Area Epitaxy

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Evidence for an incommensurate magnetic resonance in La2-xSrxCuO4

Dynamics of magnetically retained supraparticle structures in a liquid flow

Reducing the cogging torque in brushless DC motors by using conformal mappings

Dynamics of optical injection of charge and spin currents in quantum wells

DC behaviour of NbTi cable-in-conduit conductors for ITER-FEAT

Dynamics of multi-photon processes in semiconductor heterostructures

Integrated planar fluxgate sensor

Geometry considerations for transport current applications of Bi-2223 conductors with anisotropic Jc(B) in external magnetic field

Indoor radiated emission associated with power line communication systems

Long-wavelength edge-emitting lasers on gallium arsenide using InAs quantum dots embedded in InGaAs

Transient photocurrents in lead zirconate titanate thin films

Low Threshold 1.55 µm Wavelength InAsP/InGaAsP Strained Multi-Quantum Well Laser Diode Grown by Chemical Beam Epitaxy