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 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

Do útero à adoção: a experiência de mulheres férteis que adotaram uma criança

Even with all changes and ruptures related to the social roles that woman had performed, the literature had confirmed that the motherhood still configures it like one of the main roles that she hopes to play in some moment of her life. When the woman did not get pregnant or take ahead a pregnancy, some women find in adoption an alternative to play this role. This research aimed to understand the experience of being mother for adoption in the case of fertile women, but whose partner is infertile. Supported by existential-phenomenological theory, used it the narrative, how methodological instrument. Participated five women, whose adoption process followed the legal ways in the Youngness and Infancy Judgeship of Natal/RN. The results showed that in the selfish training, the woman to see herself how whose role principal is to generate children, although, she think that is natural her participation in others activities go out home too. In male infertile case is a tendency that the woman strikes the infertile status too. The adoption is an alternative to fulfill her desire of being a mother and, meanwhile, please her husband and guarantee the continuity of her love relationship. Through motherly care, the woman discover herself as a mother, what brings a new meaning for her live, independent of to generate a child. Though, exit frustration, sometimes, in association with suffering, on account of the pregnancy and childbirth absence. The end of the research suggests reflections that to become fulfilled herself as mother, the woman does not need, necessarily, to generate a child, being the maternity one of the uncountable possibilities that are shown, and that she can choose, or not, accomplish it

Propriedades estáticas e dinâmicas de multicamadas magnéticas acopladas quasiperiodicamente

In this work we study, for two different growth directions, multilayers of nanometric magnetic metallic lms grown, using Fibonacci sequences, in such a way that the thickness of the non-magnetic spacer may vary from a pair of lms to another. We applied a phenomenological theory that uses the magnetic energy to describe the behavior of the system. After we found numerically the global minimum of the total energy, we used the equilibrium angles to obtain magnetization and magnetoresistance curves. Next, we solved the equation of motion of the multilayers to nd the dispersion relation for the system. The results show that, when spacers are used with thickness so that the biquadratic coupling is strong in comparison to the bilinear one, non usual behaviors for both magnetization and magnetoresistance are observed. For example, a dependence on the parity of the Fibonacci generation utilized for constructing the system, a low magnetoresistance step in low external magnetic fields and regions that show high sensibility to small variations of the applied field. Those behaviors are not present in quasiperiodic magnetic multilayers with constant spacer thickness