Excitações elementares em super-redes quasiperiódicas com simetria espelho
In this thesis, we investigated the magnonic and photonic structures that exhibit the so-called deterministic disorder. Speci cally, we studied the effects of the quasiperiodicity, associated with an internal structural symmetry, called mirror symmetry, on the spectra of photonics and magnonics m...
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| Formato: | doctoralThesis |
| Idioma: | por |
| Publicado em: |
Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/18618 |
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| Resumo: | In this thesis, we investigated the magnonic and photonic structures that exhibit the
so-called deterministic disorder. Speci cally, we studied the effects of the quasiperiodicity,
associated with an internal structural symmetry, called mirror symmetry, on the spectra
of photonics and magnonics multilayer. The quasiperiodicity is introduced when stacked
layers following the so-called substitutional sequences. The three sequences used here
were the Fibonacci sequence, Thue-Morse and double-period, all with mirror symmetry.
Aiming to study the propagation of light waves in multilayer photonic, and spin waves
propagation in multilayer magnonic, we use a theoretical model based on transfer matrix
treatment.
For the propagation of light waves, we present numerical results that show that the
quasiperiodicity associated with a mirror symmetry greatly increases the intensity of transmission
and the transmission spectra exhibit a pro le self-similar. The return map plotted
for this system show that the presence of internal symmetry does not alter the pattern of
Fibonacci maps when compared with the case without symmetry. But when comparing
the maps of Thue-Morse and double-time sequences with their case without the symmetry
mirror, is evident the change in the pro le of the maps.
For magnetic multilayers, we work with two di erent systems, multilayer composed
of a metamagnetic material and a non-magnetic material, and multilayers composed of
two cubic Heisenberg ferromagnets. In the rst case, our calculations are carried out
in the magnetostatic regime and calculate the dispersion relation of spin waves for the
metamgnetic material considered FeBr2. We show the e ect of mirror symmetry in the
spectra of spin waves, and made the analysis of the location of bulk bands and the scaling
laws between the full width of the bands allowed and the number of layers of unit cell.
Finally, we calculate the transmission spectra of spin waves in quasiperiodic multilayers
consisting of Heisenberg ferromagnets. The transmission spectra exhibit self-similar patterns,
with regions of scaling well-de ned in frequency and the return maps indicates only
dependence of the particular sequence used in the construction of the multilayer |
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