Estudo de sistemas magneticos em estruturas periodicas / Study of magnetic systems in periodic structures

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

In this thesis we employ the holographic lithography (HL) technique to reproduce periodic patterns that were subsequently used as masks for the deposition of magnetic materials by sputtering. The structures present the same periodicity of the previously recorded mask. One advantage of this technique is the very good aspect ratio, even for areas of the order of 1000 cm2, and the low dimensions achieved. Moreover, one has a complete control of the structures? periodicity. The combination of the HL with sputtering is very oportune because this kind of deposition allows one to work with any type of material. Then, one can reproduce with great efficiency the patterns introduced by the holographic masks. The studied magnetic systems were formed by three different types of magnetic materials: Co, Ni and Ni80Fe20(permalloy). We studied the variation of the magnetic interactions among the nanostripes both as a function of the separation among them and their thickness. By comparing the results from the structured samples with the continous one it was possible observe the important role of the dipolar interaction on the coercivity. Nevertheless, we noted that the exchange field does not change for different studied samples with the same composition and thickness, indicating that this behavior is independent of the shape anisotropy and the dipolar interactions. The results of ferromagnetic resonance (FMR) showed that the anisotropy fields of the samples are smaller than the ones predicted by the magnetic measurements, indicating that we measured an effective field with the contribution of the dipolar field.

ASSUNTO(S)

magnetismo litografia magnetism periodic structures lithography holography holografia estruturas periodicas

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