Spin tunneling through an indirect barrier

Spin-dependent tunneling through an indirect bandgap barrier like the GaAs/AlAs/GaAs heterostructure along [001] direction is studied by the tight-binding method. The tunneling is characterized by the proportionality of the Dresselhaus Hamiltonians at $\Gamma$ and $X$ points in the barrier and by Fano resonances. The present results suggest that large spin polarization can be obtained for energy windows that exceed significantly the spin splitting. We also formulate two conditions that are necessary for the existence of energy windows with large polarization.Comment: 19 pages, 7 figure

Global exponential stability of classical solutions to the hydrodynamic model for semiconductors

In this paper, the global well-posedness and stability of classical solutions to the multidimensional hydrodynamic model for semiconductors on the framework of Besov space are considered. We weaken the regularity requirement of the initial data, and improve some known results in Sobolev space. The local existence of classical solutions to the Cauchy problem is obtained by the regularized means and compactness argument. Using the high- and low- frequency decomposition method, we prove the global exponential stability of classical solutions (close to equilibrium). Furthermore, it is also shown that the vorticity decays to zero exponentially in the 2D and 3D space. The main analytic tools are the Littlewood-Paley decomposition and Bony's para-product formula.Comment: 18 page

Semi- and Non-relativistic Limit of the Dirac Dynamics with External Fields

We show how to approximate Dirac dynamics for electronic initial states by semi- and non-relativistic dynamics. To leading order, these are generated by the semi- and non-relativistic Pauli hamiltonian where the kinetic energy is related to $\sqrt{m^2 + \xi^2}$ and $\xi^2 / 2m$, respectively. Higher-order corrections can in principle be computed to any order in the small parameter v/c which is the ratio of typical speeds to the speed of light. Our results imply the dynamics for electronic and positronic states decouple to any order in v/c << 1. To decide whether to get semi- or non-relativistic effective dynamics, one needs to choose a scaling for the kinetic momentum operator. Then the effective dynamics are derived using space-adiabatic perturbation theory by Panati et. al with the novel input of a magnetic pseudodifferential calculus adapted to either the semi- or non-relativistic scaling.Comment: 42 page

Studies and optimizations of encapsulation antireflection glasses for silicon solar cells panels

Date du colloque : 10/2014International audienc

Odontoid fracture that is not listed in the existing classifications: A new subtype of odontoid fracture: case report

Background: There is a significant variety of odontoid fracture classifications along with corresponding treatment strategies. There are though cases which cannot be framed within the existing classifications.Clinical presentation: We report the case of a 91 years old female patient who suffered a cervical trauma secondary to a ground level fall. The cervical CT scan revealed a particular type of odontoid fracture, unframeable within existing classifications. The fracture line was at the base of the odontoid process and continued in an oblique trajectory through the right pedicle of the axis.As treatment strategy, we opted for external immobilization in a Minerva jacket and, after 3 months, the patient is symptom free, with partial bone fusion.Conclusion: We named this rare case of odontoid fracture type II B for which external immobilization seems sufficient

The influence of the encapsulation glass properties on the performances of silicon solar cells panels

Date du colloque : 07/2014International audienc

On the properties of ITO, ZnO, ZnO:Al and NiO thin films obtained by thermal oxidation

Date du colloque : 10/2014International audienc