Ondas de spin em nanofilmes nagnéticos acoplados quasiperiodicamente
We studied the spin waves modes that can propagate in magnetic multilayers composed of ferromagnetic metallic films in the nanometer scale. The ferromagnetic films (iron) are separated and coupled through the nonmagnetic spacer films (chromium). The films that make up the multilayer are stacked in a...
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| Formato: | Dissertação |
| Idioma: | por |
| Publicado em: |
Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/16613 |
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| Resumo: | We studied the spin waves modes that can propagate in magnetic multilayers
composed of ferromagnetic metallic films in the nanometer scale.
The ferromagnetic films (iron) are separated and coupled through the nonmagnetic
spacer films (chromium). The films that make up the multilayer
are stacked in a quasiperiodic pattern, following the Fibonacci and double
period sequences. We used a phenomenological theory taking into account:
the Zeeman energy (between the ferromagnetic films and the external magnetic
field), the energy of the magneto-crystalline anisotropy (present in the
ferromagnetic films), the energy of the bilinear and biquadratic couplings
(between the ferromagnetic films) and the energy of the dipole-dipole interaction
(between the ferromagnetic films), to describe the system. The total
magnetic energy of the system is numerically minimized and the equilibrium
angles of the magnetization of each ferromagnetic film are determined. We
solved the equation of motion of the multilayer to find the dispersion relation
for the system and, as a consequence, the spin waves modes frequencies.
Our theoretical results show that, in the case of trilayers (Fe/Cr/Fe), our
model reproduces with excellent agreement experimental results of Brillouin
light scattering, known from the literature, by adjusting the physical parameters
of the nanofilms. Furthermore, we generalize the model to N ferromagnetic
layers which allowed us to determine how complex these systems
become when we increase the number of components. It is worth noting
that our theoretical calculations generalize all the results known from the
literature |
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