16 research outputs found
Topological defects, pattern evolution, and hysteresis in thin magnetic films
Nature of the magnetic hysteresis for thin films is studied by the
Monte-Carlo simulations. It is shown that a reconstruction of the magnetization
pattern with external field occurs via the creation of vortex-antivortex pairs
of a special kind at the boundaries of stripe domains. It is demonstrated that
the symmetry of order parameter is of primary importance for this problem, in
particular, the in-plane magnetic anisotropy is necessary for the hysteresis.Comment: Accepted to EPL; 7 pages, 3 color figure
Intrinsic nanoscale inhomogeneity in ordering systems due to elastic-mediated interactions
Phase diagram and pattern formation in two-dimensional Ising model with
coupling between order parameter and lattice vibrations is investigated by
Monte-Carlo simulations. It is shown that if the coupling is strong enough (or
phonons are soft enough) a short-range order exists in disordered phase for a
broader temperature interval. Different types of this short-range order
(stripe-like, checkboard-like, etc.) depending on the temperature and model
parameters are investigated. With further increase of the coupling, a
reconstruction of the ground state happens and new ordered phases appear at low
enough temperatures.Comment: final version, Europhys. Lett., accepte
Electromagnetic field correlations between differently directed modes in elastic light scattering
We have experimentally investigated the intensity correlations in light generated by elastic scattering of a standing pump wave by macroscopic objects, i.e., particles with sizes on the order of a micron. We have observed that the spatial correlation function is a maximum for oppositely directed modes of scattered light. We show that this phenomenon is analogous to the Brown-Twiss effect for a pseudothermal source.
Intensity interference in Bragg scattering by acoustic waves with thermal statistics
Angular distributions of the intensity and the fourth-order correlation function are studied for light scattered by acoustic waves with thermal statistics. In the case when the beam diameter exceeds the coherence length of the acoustic wave, the fourth-order correlation function is found to contain an interference structure, whereas the intensity angular distribution has a one-peak shape
Effect of magnetism on kinetics of gamma-alpha transformation and pattern formation in iron
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