423 research outputs found
Magnetoelectric Response of the Time-Reversal Invariant Helical Metal
We derive compact analytical expressions for the coupled spin-charge
susceptibility of a clean helical metal at the surface of a three dimensional
topological insulator (TI). These expressions lead to unconventional
non-collinear RKKY interactions between two impurity magnetic moments placed on
the surface of a TI, and predict the generation of electric currents by
time-dependent magnetic moments. We determine the influence of gate and bias
voltages on the interlayer exchange coupling between two single-domain
ferromagnetic monolayers deposited on top of a TI.Comment: 4 pages, 2 figures; submitted to Phys. Rev. B R
Non-Adiabatic Spin Transfer Torque in Real Materials
The motion of simple domain walls and of more complex magnetic textures in
the presence of a transport current is described by the
Landau-Lifshitz-Slonczewski (LLS) equations. Predictions of the LLS equations
depend sensitively on the ratio between the dimensionless material parameter
which characterizes non-adiabatic spin-transfer torques and the Gilbert
damping parameter . This ratio has been variously estimated to be close
to 0, close to 1, and large compared to 1. By identifying as the
influence of a transport current on , we derive a concise, explicit and
relatively simple expression which relates to the band structure and
Bloch state lifetimes of a magnetic metal. Using this expression we demonstrate
that intrinsic spin-orbit interactions lead to intra-band contributions to
which are often dominant and can be (i) estimated with some confidence
and (ii) interpreted using the "breathing Fermi surface" model.Comment: 18 pages, 9 figures; submitted to Phys. Rev.
Weak Localization and Antilocalization in Topological Insulator Thin Films with Coherent Bulk-Surface Coupling
We evaluate quantum corrections to conductivity in an electrically gated thin
film of a three-dimensional (3D) topological insulator (TI). We derive
approximate analytical expressions for the low-field magnetoresistance as a
function of bulk doping and bulk-surface tunneling rate. Our results reveal
parameter regimes for both weak localization and weak antilocalization, and
include diffusive Weyl semimetals as a special case.Comment: After publication, we have noticed and corrected two small but
potentially misleading typographic errors in Eqs. (2.27) and (2.29), where
the definitions of \tau_s and \tau_v were mistakenly switched. Once these
typographic errors are fixed, all the results remain unchanged. An Erratum
will be published in PR
Development of the instrumentation of the botafoc breakwater nº 8 caisson
Balearic Port Authority has developed an instrumentation system for the #8 caisson of the Botafoc breakwater that integrates 12 pressure sensors located at three surfaces, two in contact with the sea water and another with the bottom. This design was completed with an inertial system that measures the angular velocities and the accelerations over the three Cartesian axes. Consequently, the system measures actions (pressures) and reactions (movements and accelerations) experimented by the caisson, due to sea waves and/or other service loads. R+D department of the Port Authority and Polytechnic University of Madrid are working on two directions, the development of new theories on vertical breakwater design that go beyond Goda and Sainflou, and on the creation of a real-time critical structure alarm system, based on the instrumentation installed. This alarm system has two main parts: the instrumentation itself that collects data and processes it on real-time (the data processing compares the pressure law suffered by the caisson in every step process with the design critical state of the caisson, in this case the Goda pressure law for a 6.5 m wave), giving a security coefficient that points out the risk level on real-time; and the alarm system consisting of a monitoring panel located in the Port Control Center that shows the risk level and advises in case of an incidental evacuation of this critical portuary installation
Resonant Scattering and Recombination in CAL 87
The eclipsing supersoft X-ray binary CAL 87 has been observed with Chandra on
August 13/14, 2001 for nearly 100 ksec, covering two full orbital cycles and
three eclipses. The shape of the eclipse light curve derived from the
zeroth-order photons indicates that the size of the X-ray emission region is
about 1.5 solar radii. The ACIS/LETG spectrum is completely dominated by
emission lines without any noticeable continuum. The brightest emission lines
are significantly redshifted and double-peaked, suggestive of emanating in a
2000 km/s wind. We model the X-ray spectrum by a mixture of recombination and
resonant scattering. This allows us to deduce the temperature and luminosity of
the ionizing source to be kT = 50-100 eV and L_X = 5E37 erg/s.Comment: To appear in Proceedings of IAU Coll. 194 "Compact binaries in the
Galaxy and beyond" (Rev. Mex. A&A Conf. Series), eds. G. Tovmassian and E.
Sio
Derecho y la administración de justicia
In this writing it’s reflected the possibility of a better justice since the implementation of a project of decentralization as that of “Casa de la Justicia” (House of Justice) developed by Attorney General of the Buenos Aires Province in order to provide better access to justice and the ways to obtain an alternative dispute resolution of a familyEn este trabajo reflexionamos, sobre la posibilidad de una mejor justicia desde la implementación de uno de los proyectos de descentralización como es el de “Casa de Justicia” desarrollado por la Procuración General de la Provincia de Buenos Aires, con la finalidad de brindar un mejor acceso a la justicia y los caminos para obtener una resolución alternativa de conflictos de índole familia
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