2,369 research outputs found
Shannon entropy and particle decays
We deploy Shannon's information entropy to the distribution of branching
fractions in a particle decay. This serves to quantify how important a given
new reported decay channel is, from the point of view of the information that
it adds to the already known ones. Because the entropy is additive, one can
subdivide the set of channels and discuss, for example, how much information
the discovery of a new decay branching would add; or subdivide the decay
distribution down to the level of individual quantum states (which can be
quickly counted by the phase space). We illustrate the concept with some
examples of experimentally known particle decay distributions.Comment: 12 pages, 18 plots; to appear in Nuclear Physics
The design and verification of Mumax3
We report on the design, verification and performance of mumax3, an
open-source GPU-accelerated micromagnetic simulation program. This software
solves the time- and space dependent magnetization evolution in nano- to micro
scale magnets using a finite-difference discretization. Its high performance
and low memory requirements allow for large-scale simulations to be performed
in limited time and on inexpensive hardware. We verified each part of the
software by comparing results to analytical values where available and to
micromagnetic standard problems. mumax3 also offers specific extensions like
MFM image generation, moving simulation window, edge charge removal and
material grains
Individual skyrmion manipulation by local magnetic field gradients
Magnetic skyrmions are topologically protected spin textures, stabilised in systems with strong Dzyaloshinskii-Moriya interaction (DMI). Several studies have shown that electrical currents can move skyrmions efficiently through spin-orbit torques. While promising for technological applications, current-driven skyrmion motion is intrinsically collective and accompanied by undesired heating effects. Here we demonstrate a new approach to control individual skyrmion positions precisely, which relies on the magnetic interaction between sample and a magnetic force microscopy (MFM) probe. We investigate perpendicularly magnetised X/CoFeB/MgO multilayers, where for X = W or Pt the DMI is sufficiently strong to allow for skyrmion nucleation in an applied field. We show that these skyrmions can be manipulated individually through the local field gradient generated by the scanning MFM probe with an unprecedented level of accuracy. Furthermore, we show that the probe stray field can assist skyrmion nucleation. Our proof-of-concepts results pave the way towards achieving current-free skyrmion control
Chiral spin textures creation and dynamics in a rectangular nanostructure
Controlled creation of stable chiral spin textures is required to use them as
an energy-efficient information carrier in spintronics. Here we have studied
the stable creation of isolated chiral spin texture (skyrmion and antiskyrmion)
and its pair through the magnetization reversal of a rectangular nanostructure
using spin-polarized currents. An isolated spin texture is created through a
negative current pulse. Dynamics of the stable spin texture are explored under
external magnetic fields, and the resonant frequencies are calculated. A stable
skyrmion pair is created using an asymmetric current pulse, and their
interaction is studied using the Thiele equation. The stability of isolated or
paired spin texture depends on the DMI strength, spin-polarized current
density, and pulse duration. In addition, the stability of the skyrmion pair
depends on their initial separation, and a threshold for the separation between
skyrmions of 78 nm is observed.Comment: 29 pages, 11 figures, 2 extra figure
¿Es el efecto de las ventas en corto un factor determinante en la formación de precios? : el caso del Bitcoin
Este trabajo analiza la relación que tienen las ventas en corto, los sesgos de los agentes junto la interacción de los fundamentales de oferta y demanda respecto la formación de precios en el mercado del Bitcoin. Dentro del análisis encontramos que las tendencias aportadas en la literatura se mantienen en cuanto a las ventas en corto y sus restricciones a pesar de no encontrar evidencia estadÃstica.This paper analyzes the relationship that short sales have, the biases of the agents together with the interaction of the fundamentals of supply and demand regarding price formation in the Bitcoin market. Within the analysis we will find the trends provided in the literature, let's verify regarding short sales and their restrictions despite not finding statistical evidence.MagÃster en EconomÃaMaestrÃ
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