47,154 research outputs found
Synchronization in the presence of memory
We study the effect of memory on synchronization of identical chaotic systems
driven by common external noises. Our examples show that while in general
synchronization transition becomes more difficult to meet when memory range
increases, for intermediate ranges the synchronization tendency of systems can
be enhanced. Generally the synchronization transition is found to depend on the
memory range and the ratio of noise strength to memory amplitude, which
indicates on a possibility of optimizing synchronization by memory. We also
point out on a close link between dynamics with memory and noise, and recently
discovered synchronizing properties of networks with delayed interactions
How hole defects modify vortex dynamics in ferromagnetic nanodisks
Defects introduced in ferromagnetic nanodisks may deeply affect the structure
and dynamics of stable vortex-like magnetization. Here, analytical techniques
are used for studying, among other dynamical aspects, how a small cylindrical
cavity modify the oscillatory modes of the vortex. For instance, we have
realized that if the vortex is nucleated out from the hole its gyrotropic
frequencies are shifted below. Modifications become even more pronounced when
the vortex core is partially or completely captured by the hole. In these
cases, the gyrovector can be partially or completely suppressed, so that the
associated frequencies increase considerably, say, from some times to several
powers. Possible relevance of our results for understanding other aspects of
vortex dynamics in the presence of cavities and/or structural defects are also
discussed.Comment: 9 pages, 4 page
Finite-size effects in roughness distribution scaling
We study numerically finite-size corrections in scaling relations for
roughness distributions of various interface growth models. The most common
relation, which considers the average roughness . This illustrates how
finite-size corrections can be obtained from roughness distributions scaling.
However, we discard the usual interpretation that the intrinsic width is a
consequence of high surface steps by analyzing data of restricted
solid-on-solid models with various maximal height differences between
neighboring columns. We also observe that large finite-size corrections in the
roughness distributions are usually accompanied by huge corrections in height
distributions and average local slopes, as well as in estimates of scaling
exponents. The molecular-beam epitaxy model of Das Sarma and Tamborenea in 1+1
dimensions is a case example in which none of the proposed scaling relations
works properly, while the other measured quantities do not converge to the
expected asymptotic values. Thus, although roughness distributions are clearly
better than other quantities to determine the universality class of a growing
system, it is not the final solution for this task.Comment: 25 pages, including 9 figures and 1 tabl
Temperature effect on (2+1) experimental Kardar-Parisi-Zhang growth
We report on the effect of substrate temperature (T) on both local structure
and long-wavelength fluctuations of polycrystalline CdTe thin films deposited
on Si(001). A strong T-dependent mound evolution is observed and explained in
terms of the energy barrier to inter-grain diffusion at grain boundaries, as
corroborated by Monte Carlo simulations. This leads to transitions from
uncorrelated growth to a crossover from random-to-correlated growth and
transient anomalous scaling as T increases. Due to these finite-time effects,
we were not able to determine the universality class of the system through the
critical exponents. Nevertheless, we demonstrate that this can be circumvented
by analyzing height, roughness and maximal height distributions, which allow us
to prove that CdTe grows asymptotically according to the Kardar-Parisi-Zhang
(KPZ) equation in a broad range of T. More important, one finds positive
(negative) velocity excess in the growth at low (high) T, indicating that it is
possible to control the KPZ non-linearity by adjusting the temperature.Comment: 6 pages, 5 figure
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