10,788 research outputs found
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,
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
Evolución de fascies abanico aluvial-fluvial-lacustre en el Plioceno de la Depresión de Guadix-Baza
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