Transport in Selectively Magnetically Doped Topological Insulator Wires

We study the electronic and transport properties of a topological insulator nanowire including selective magnetic doping of its surfaces. We use a model which is appropriate to describe materials like Bi$_2$Se$_3$ within a k.p approximation and consider nanowires with a rectangular geometry. Within this model the magnetic doping at the (111) surfaces induces a Zeeman field which opens a gap at the Dirac cones corresponding to the surface states. For obtaining the transport properties in a two terminal configuration we use a recursive Green function method based on a tight-binding model which is obtained by discretizing the original continuous model. For the case of uniform magnetization of two opposite nanowire (111) surfaces we show that the conductance can switch from a quantized value of $e^2/h$ (when the magnetizations are equal) to a very small value (when they are opposite). We also analyze the case of non-uniform magnetizations in which the Zeeman field on the two opposite surfaces change sign at the middle of the wire. For this case we find that conduction by resonant tunneling through a chiral state bound at the middle of the wire is possible. The resonant level position can be tuned by imposing an Aharonov-Bohm flux through the nanowire cross section.Comment: 8 pages, 7 figure

Incorporaciones léxicas en el "Vocabulario de las dos lenguas toscana y castellana" de Cristóbal de las Casas

"El Vocabulario de las dos lenguas toscana y castellana" de Cristóbal de las Casas es el primer diccionario ítaloespañol que se conoce. Fue publicado en Sevilla en 1570 y es fruto de estrechos contactos entre españoles e italianos durante los siglos XVI y XVII. Aquí se analizan los estudios lexicográficos de Alfonso de Palencia (Vocabulario Universal) y A. de Nebrija (Vocabulario Español-Latino y su diccionario Latino-Español). Se pone de manifiesto la originalidad del Vocabulario toscano-castellano con palabras no encontradas ni en el de Palencia ni en el de Nebrija, muchas de ellas documentadas por primera vez en España."El vocabulario de las dos lenguas toscana y castellana​​" Cristóbal de las Casas is the first known ítaloespañol dictionary. It was published in Seville in 1570 and is the result of close contact between Spaniards and Italians during the sixteenth and seventeenth centuries. The lexicographical studies Alfonso de Palencia (Universal Vocabulary) and A. de Nebrija (Vocabulary Spanish -Latin and Latin - Spanish Dictionary) are analyzed. It shows the originality of the Tuscan - Castilian vocabulary with words not found in either the Palencia or the de Nebrija , many documented for the first time in Spain

OVII and OVIII line emission in the diffuse soft X-ray background: heliospheric and galactic contributions

We study the 0.57 keV (O VII triplet) and 0.65 keV (O VIII) diffuse emission generated by charge transfer collisions between solar wind (SW) oxygen ions and interstellar H and He neutral atoms in the inner Heliosphere. These lines which dominate the 0.3-1.0 keV energy interval are also produced by hot gas in the galactic halo (GH) and possibly the Local Interstellar Bubble (LB). We developed a time-dependent model of the SW Charge-Exchange (SWCX) X-ray emission, based on the localization of the SW Parker spiral at each instant. We include input SW conditions affecting three selected fields, as well as shadowing targets observed with XMM-Newton, Chandra and Suzaku and calculate X-ray emission fot O VII and O VIII lines. We determine SWCX contamination and residual emission to attribute to the galactic soft X-ray background. We obtain ground level intensities and/or simulated lightcurves for each target and compare to X-ray data. The local 3/4 keV emission (O VII and O VIII) detected in front of shadowing clouds is found to be entirely explained by the CX heliospheric emission. No emission from the LB is needed at these energies. Using the model predictions we subtract the heliospheric contribution to the measured emission and derive the halo contribution. We also correct for an error in the preliminary analysis of the Hubble Deep Field North (HDFN).Comment: 21 pages (3 on-line), 10 figures (4 on-line), accepted for publication in Astronomy and Astrophysic

A new nearby pulsar wind nebula overlapping the RX J0852.0-4622 supernova remnant

Energetic pulsars can be embedded in a nebula of relativistic leptons which is powered by the dissipation of the rotational energy of the pulsar. The object PSR J0855-4644 is an energetic and fast-spinning pulsar (Edot = 1.1x10^36 erg/s, P=65 ms) discovered near the South-East rim of the supernova remnant (SNR) RX J0852.0-4622 (aka Vela Jr) by the Parkes multibeam survey. The position of the pulsar is in spatial coincidence with an enhancement in X-rays and TeV gamma-rays, which could be due to its putative pulsar wind nebula (PWN). The purpose of this study is to search for diffuse non-thermal X-ray emission around PSR J0855-4644 to test for the presence of a PWN and to estimate the distance to the pulsar. An X-ray observation was carried out with the XMM-Newton satellite to constrain the properties of the pulsar and its nebula. The absorption column density derived in X-rays from the pulsar and from different regions of the rim of the SNR was compared with the absorption derived from the atomic (HI) and molecular (12CO) gas distribution along the corresponding lines of sight to estimate the distance of the pulsar and of the SNR. The observation has revealed the X-ray counterpart of the pulsar together with surrounding extended emission thus confirming the existence of a PWN. The comparison of column densities provided an upper limit to the distance of the pulsar PSR J0855-4644 and the SNR RX J0852.0-4622 (d<900 pc). Although both objects are at compatible distances, we rule out that the pulsar and the SNR are associated. With this revised distance, PSR J0855-4644 is the second most energetic pulsar, after the Vela pulsar, within a radius of 1 kpc and could therefore contribute to the local cosmic-ray e-/e+ spectrum.Comment: 10 pages, 9 Figures. Accepted for publication in A&

EMI Reduction Via Resonator Coils in Glassless Integrated Domestic Induction Systems

This paper explores the magnetic flux emissions of induction heating systems compared with inductively coupled heating systems. Inductively coupled heating uses a resonator coil attached to the ferromagnetic load in order to improve energy transfer from the appliance to the load. The magnetic flux emissions of both kinds of systems are simulated, and their dependence on coil current and turn number is outlined. The paper focuses on emitted near field, whose measurement and limits are determined by norm. Several prototypes are developed and tested to verify the simulation