1,026 research outputs found
A skyrmion-based spin-torque nano-oscillator
A model for a spin-torque nano-oscillator based on the self-sustained
oscillation of a magnetic skyrmion is presented. The system involves a circular
nanopillar geometry comprising an ultrathin film free magnetic layer with a
strong Dzyaloshinkii-Moriya interaction and a polariser layer with a
vortex-like spin configuration. It is shown that spin-transfer torques due to
current flow perpendicular to the film plane leads to skyrmion gyration that
arises from a competition between geometric confinement due to boundary edges
and the vortex-like polarisation of the spin torques. A phenomenology for such
oscillations is developed and quantitative analysis using micromagnetics
simulations is presented. It is also shown that weak disorder due to random
anisotropy variations does not influence the main characteristics of the
steady-state gyration.Comment: 15 pages, 6 figure
Single spin-torque vortex oscillator using combined bottom-up approach and e-beam lithography
A combined bottom-up assembly of electrodeposited nanowires and electron beam
lithography technique has been developed to investigate the spin transfer
torque and microwave emission on specially designed nanowires containing a
single Co/Cu/Co pseudo spin valve. Microwave signals have been obtained even at
zero magnetic field. Interestingly, high frequency vs. magnetic field
tunability was demonstrated, in the range 0.4 - 2 MHz/Oe, depending on the
orientation of the applied magnetic field relative to the magnetic layers of
the pseudo spin valve. The frequency values and the emitted signal frequency as
a function of the external magnetic field are in good quantitative agreement
with the analytical vortex model as well as with micromagnetic simulations.Comment: 9 pages, 4 figure
Preparación de agregados orientados de arcilla mediante extensor
Se detalla un método nuevo para la preparación de agregados orientados de arcilla para sus análisis por Difracción de Rayos X. Se trata de emplear un extensor para obtener un grosor constante de material, que por su delgadez seca rápidamente, economizándose tiempo y espacio en el laboratorio, obteniéndose además mejores resultados que con el método convencional
Phase diagram of silicon from atomistic simulations
In this letter we present a calculation of the temperature-pressure phase
diagram of Si in a range of pressures covering from -5 to 20 GPa and
temperatures up to the melting point. The phase boundaries and triple points
between the diamond, liquid, -Sn and clathrate phases are
reported. We have employed efficient simulation techniques to calculate free
energies and to numerically integrate the Clausius-Clapeyron equation, combined
with a tight binding model capable of an accuracy comparable to that of
first-principles methods. The resulting phase diagram agrees well with the
available experimental data.Comment: 5 pages, 1 figure, accepted in PR
Spin injection in a single metallic nanoparticle: a step towards nanospintronics
We have fabricated nanometer sized magnetic tunnel junctions using a new
nanoindentation technique in order to study the transport properties of a
single metallic nanoparticle. Coulomb blockade effects show clear evidence for
single electron tunneling through a single 2.5 nm Au cluster. The observed
magnetoresistance is the signature of spin conservation during the transport
process through a non magnetic cluster.Comment: 3 page
Modeling Management Operations in Agricultural Production Simulators
Rosana G. Moreira, Editor-in-Chief; Texas A&M UniversityThis is a Technical Paper from International Commission of Agricultural Engineering (CIGR, Commission Internationale du Genie Rural) E-Journal Volume 5 (2003): M-J. Cros, F. Garcia, R. Martin-Clouaire, and J-P. Rellier. Modeling Management Operations in Agricultural Production Simulators. Vol. V. May 2003
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