Coverage effects on the magnetism of Fe/MgO(001) ultrathin films

Different aspects of the structure-magnetism and morphology-magnetism correlation in the ultrathin limit are studied in epitaxial Fe films grown on MgO(001). In the initial stages of growth the presence of substrate steps, intrinsically higher than an Fe atomic layer, prevent the connection between Fe islands and hence the formation of large volume magnetic regions. This is proposed as an explanation to the superparamagnetic nature of ultrathin Fe films grown on MgO in addition to the usually considered islanded, or Vollmer-Weber, growth. Using this model, we explain the observed transition from superparamagnetism to ferromagnetism for Fe coverages above 3 monolayers (ML). However, even though ferromagnetism and magnetocrystalline anisotropy are observed for 4 ML, complete coverage of the MgO substrate by the Fe ultrathin films only occurs around 6 ML as determined by polar Kerr spectra and simulations that consider different coverage situations. In annealed 3.5 ML Fe films, shape or configurational anisotropy dominates the intrinsic magnetocrystalline anisotropy, due to an annealing induced continuous to islanded morphological transition. A small interface anisotropy in thicker films is observed, probably due to dislocations observed at the Fe¿MgO(001) interface.

MgO/Ag(001) interface structure and STM images from first principles

The interface of MgO/Ag(001) has been studied with density functional theory applied to slabs. We have found that regular MgO films show a small adhesion to the silver substrate, the binding can be increased in off-stoichiometric regimes, either by the presence of O vacancies at the oxide film or by a small excess of O atoms at the interface between the ceramic to the metal. By means of theoretical methods, the scanning tunneling microscopy signatures of these films is also analyzed in some detail. For defect free deposits containing 1 or 2 ML and at low voltages, tunnelling takes place from the surface Ag substrate, and at large positive voltages Mg atoms are imaged. If defects, oxygen vacancies, are present on the surface of the oxide they introduce much easier channels for tunnelling resulting in big protrusions and controlling the shape of the image, the extra O stored at the interface can also be detected for very thin films.

El Acto Legislativo 001 de 2003 y el comportamiento electoral de partidos y movimientos políticos, en las elecciones a la Cámara de Representantes 2002 y 2006. Estudio de caso : Antioquia

El presente trabajo tiene como objetivo mostrar los efectos del acto legislativo 01 de 2003, en las elecciones a la Cámara de Representantes de 2006 en el Departamento de Antioquia. Esto con el fin de mostrar el comportamiento de los partidos y movimientos políticos antes y después de entrar en vigencia la reforma. El objetivo principal de la investigación es identificar y entender la cotidianidad y las prácticas políticas a las que los partidos tradicionales y las nuevas organizaciones estaban acostumbradas después de la constitución de 1991. Estas reglas de juego planteadas por las Constitución Política, cambiaron el panorama político tanto para los partidos tradicionalistas, como para las nuevas organizaciones que querían y reclamaban reconocimiento, participación y poder. Reglas que se transformaron con la reforma política, y específicamente con el Acto legislativo 01 de 2003, cambiando el escenario político y por ende el comportamiento electoral.

EdShare workshop 001

Materials and links related to staff workshop on using EdShare.

Implantación de un sistema de gestión ambiental de acuerdo con la Norma UNE-EN ISO 14 001: 2004 en institutos de secundaria : una experiencia en IES Ramón y Cajal, de Valladolid.

Se presentan las principales fases del proyecto de implantación de un sistema de gestión ambiental de acuerdo con al normativa española, en el IES Ramón y Cajal de Valladolid. En una primera fase se procede al diagnóstico ambiental inicial y a la formación por objetivos y áreas de trabajo de los grupos establecidos. A continuación, se procede a la elaboración de la documentación necesaria, entre ella, la política ambiental del IES, y la implantación del sistema. La fase de seguimiento del sistema se realiza a través de auditorías internas y revisiones por parte de la dirección. Finalmente, se obtiene la certificación de la norma por parte de SGS.

Inconstitucionalidad por omisión en la jurisprudencia de la Corte Constitucional ecuatoriana. Sentencia No. 001-1L-SIO-CC (caso No. 0005-10-IO) [Jurisprudencia]

El presente trabajo pretende mostrar de manera objetiva y técnica, las motivaciones, contenidos y demás elementos de sustento utilizados por la Corte Constitucional ecuatoriana en el control abstracto de inconstitucionalidad por omisión normativa. Previo el análisis de la sentencia se presentan conceptos relativos al control de constitucionalidad por omisión en el derecho comparado y en la doctrina, además se hace un breve recorrido histórico del aparecimiento de la mencionada institución jurídica. Finalmente, se revisa la sentencia en cada una de sus partes y se van describiendo los aspectos más relevantes y conflictivos.

Análisis de la sentencia n.º 001-10-SIN-CC. Casos n.º 0008-09-IN y 0011-09-IN sobre acción de inconstitucionalidad en contra de la Ley de Minería y efectos posteriores (Jurisprudencia)

This paper aims to analyze the decision issued by the Constitutional Court for Transition within the unconstitutionality presented against the Mining Act. Proponents, in the main, formal allege unconstitutional by the Mining Law have been issued by the Committee on Legislation and Oversight (National Assembly during the Transitional Period after the adoption of the 2008 Constitution) without the prior execution of a legislative pre query, this query being a collective right of national, indigenous peoples and communities recognized in Article 57 paragraph 17 of the Constitution of the Republic. The Constitutional Court ruled Transition to reject the unconstitutionality confirming the constitutionality of the regulatory body and the substantial and non-formal pre-legislative consultation.

Scanning tunneling microscopy and molecular dynamics study of the Li2TiO3(001) surface

We have investigated the (001) surface structure of lithium titanate (Li2TiO3) using auger electron spectroscopy (AES), low-energy electron diffraction (LEED), and scanning tunneling microscopy (STM). Li2TiO3 is a potential fusion reactor blanket material. After annealing at 1200 K, LEED demonstrated that the Li2TiO3(001) surface was well ordered and not reconstructed. STM imaging showed that terraces are separated in height by about 0.3 nm suggesting a single termination layer. Moreover, hexagonal patterns with a periodicity of ∼0.4 nm are observed. On the basis of molecular dynamics (MD) simulations, these are interpreted as a dynamic arrangement of Li atoms.

Lines of heavy elements and Fe II in the UV of CS 31082-001

The abundance of heavy r-elements may provide a better understanding of the r-process, and the determination of several reference r-elements should allow a better determination of a star`s age. The space UV region (lambda < 3000 angstrom) presents a large number of lines of the heavy elements, and in the case of some elements, such as Bi, Pt, Au, detectable lines are not available elsewhere. The extreme ""r-process star"" CS 31082-001 ([Fe/H] = -2.9) was observed in the space UV to determine abundances of the heaviest stable elements, using STIS on board Hubble Space Telescope.

Hybrid reflections in InGaP/GaAs(001) by synchrotron radiation multiple diffraction

Hybrid reflections (HRs) involving substrate and layer planes (SL type) [Morelhao et al., Appl. Phys. Len. 73 (15), 2194 (1998)] observed in Chemical Beam Epitaxy (CBE) grown InGaP/GaAs(001) structures were used as a three-dimensional probe to analyze structural properties of epitaxial layers. A set of (002) rocking curves (omega-scan) measured for each 15 degrees in the azimuthal plane was arranged in a pole diagram in phi for two samples with different layer thicknesses (#A -58 nm and #B - 370 nm) and this allowed us to infer the azimuthal epilayer homogeneity in both samples. Also, it was shown the occurrence of (1 (1) over bar3) HR detected even in the thinner layer sample. Mappings of the HR diffraction condition (omega:phi) allowed to observe the crystal truncation rod through the elongation of HR shape along the substrate secondary reflection streak which can indicate in-plane match of layer/substrate lattice parameters. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Magnetism of Co overlayers and nanostructures on W(001): A first-principles study

The magnetic properties of Co nanostructures and a Co monolayer on W(001) have been studied in the framework of density functional theory. Different geometries such as planar and three-dimensional clusters have been considered, with cluster sizes varying between 2 and 13 atoms. The calculations were performed using the real-space linear muffin-tin orbital method (RS-LMTO-ASA). With respect to the stability of the magnetic state, we predict an antiferromagnetic (AFM) structure for the ground state of the planar Co clusters and a ferromagnetic (FM) state for the three-dimensional clusters. For the three-dimensional clusters, one of the AFM arrangements leads to frustration due to the competing FM and AFM exchange interactions between different atoms in the cluster, and gives rise to a non-collinear state with energy close to that of the FM ground state. The relative role of the Co-Co and Co-W exchange interactions is also investigated. (C) 2007 Elsevier B.V. All rights reserved.