Van der Waals spin valves

We propose spin valves where a 2D non-magnetic conductor is intercalated between two ferromagnetic insulating layers. In this setup, the relative orientation of the magnetizations of the insulating layers can have a strong impact on the in-plane conductivity of the 2D conductor. We first show this for a graphene bilayer, described with a tight-binding model, placed between two ferromagnetic insulators. In the anti-parallel configuration, a band gap opens at the Dirac point, whereas in the parallel configuration, the graphene bilayer remains conducting. We then compute the electronic structure of graphene bilayer placed between two monolayers of the ferromagnetic insulator CrI$_3$, using density functional theory. Consistent with the model, we find that a gap opens at the Dirac point only in the antiparallel configuration.Comment: 5 pages, 4 figure

Giant magnetic anisotropy at nanoscale: overcoming the superparamagnetic limit

It has been recently observed for palladium and gold nanoparticles, that the magnetic moment at constant applied field does not change with temperature over the range comprised between 5 and 300 K. These samples with size smaller than 2.5 nm exhibit remanence up to room temperature. The permanent magnetism for so small samples up to so high temperatures has been explained as due to blocking of local magnetic moment by giant magnetic anisotropies. In this report we show, by analysing the anisotropy of thiol capped gold films, that the orbital momentum induced at the surface conduction electrons is crucial to understand the observed giant anisotropy. The orbital motion is driven by localised charge and/or spin through spin orbit interaction, that reaches extremely high values at the surfaces. The induced orbital moment gives rise to an effective field of the order of 103 T that is responsible of the giant anisotropy.Comment: 15 pages, 2 figures, submitted to PR

Cotilo recubierto con hidroxiapatita de la artroplastia Omnifit: resultados a medio plazo

Las cúpulas acetabulares roscadas han mostrado malos resultados en períodos medios de evolución. Aunque la sujeción inmediata es excelente, con el paso del tiempo se ha comprobado la ausencia de fijación, mostrando un alto porcentaje de movilizaciones. Una alternativa para evitar esos fracasos es el recubrimiento de estos cotilos con hidroxiapatita. Hemos revisado clínica y radiográficamente 36 casos de artroplastias Omnifit con cotilo roscado y recubierto de hidroxiapatita, con un tiempo medio de seguimiento de 58 meses. Diez pacientes presentaban dolor en región inguinal. Sólo el 63,9% de los cotilos se encontraban radiográficamente integrados, habiendo sufrido una clara movilización seis que precisaron cirugía de revisión acetabular; otros siete mostraban signos radiológicos de probable inestabilidad. El recubrimiento con hidroxiapatita no asegura una buena fijación en los cotilos roscados Omnifit por lo que recomendamos componentes acetabulares implantados a presión con posibilidad de sujeción adicional con tornillos.The threaded acetabular cups have shown mid-term bad results. Though the immediate fixation is excellent, as time goes by it has been proven the absence of fixation, appearing a high percentage of mobilizations. An alternative to avoid those failures is the hydroxyapatite coated implant. We have analysed clinically and radiographically 36 cases of Omnifit arthroplasties with cup threaded and coated with hydroxyapatite with an average time of follow-up of 58 months. Ten patients had pain in the hip. Only 63.9% of the acetabular cups were found to be radiographically integrated, six having suffered a clear mobilization requiring surgical review. Seven showed radiological signs of probable instability. The hydroxytapatite coatings does not assure a good fixation in the Omnifit threaded cups, therefore we recommend press fit acetabular components with the possibility of additional fixation with screws

Some results on the eigenfunctions of the quantum trigonometric Calogero-Sutherland model related to the Lie algebra E6

The quantum trigonometric Calogero-Sutherland models related to Lie algebras admit a parametrization in which the dynamical variables are the characters of the fundamental representations of the algebra. We develop here this approach for the case of the exceptional Lie algebra E6.Comment: 17 pages, no figure

Ensayo de fertilización foliar sobre regenerado de pino rodeno en Cuéllar (Segovia)

El regenerado de Pinus pinaster Ait. en la tierra de pinares segoviana presenta frecuentemente, en estado de monte bravo, un desarrollo deficiente de la guía y de las ramas del tercio superior de la copa. El objetivo del presente estudio es tratar de determinar si este deficiente desarrollo está relacionado con alguna carencia nutricional. Para ello se realiza un ensayo de fertilización foliar y se analiza su influencia sobre la Longitud de las acículas y la Longitud de los ramillos desarrollados en el periodo vegetativo siguiente a la fertilización. Se consideran cuatro localizaciones diferentes y tres tratamientos distintos (Testigo, T, sin fertilización; fertilización simple, F; y fertilización doble, FF)

Rasgos generales estratigráficos y sedimentológicos del macizo urgoniano de Gorbea, Región Vasco-Cantábrica Central

Se diferencian 8 unidades urgonianas dentro de un esquema de plataforma mixta con individualización final de un banco carbona-iado, en el Aptiense-Albiense medio del macizo de Gorbea (Vizca ya). Pulsaciones tectónicas sinsedimentarias, incluyendo fracturación blandel zócalo y halocinesis, además de variaciones relativas del nivel del tectómar, constituyen los principales controles en el desarrollo y evolución de la plataforma

Transformation Optics Approach to Plasmon-Exciton Strong Coupling in Nanocavities

We investigate the conditions yielding plasmon-exciton strong coupling at the single emitter level in the gap between two metal nanoparticles. A quasi-analytical transformation optics approach is developed that makes possible a thorough exploration of this hybrid system incorporating the full richness of its plasmonic spectrum. This allows us to reveal that by placing the emitter away from the cavity center, its coupling to multipolar dark modes of both even and odd parity increases remarkably. This way, reversible dynamics in the population of the quantum emitter takes place in feasible implementations of this archetypal nanocavity.Comment: 5 pages, 4 figure