Propriedades magnÃticas e Ãpticas de filmes finos rugosos

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

In this dissertation we study the influence of susbtrate roughness on the magnetic and optical properties of polycrystalline permalloy (Py) films and the optical properties of thin silver (Ag) films, when deposited on this support. The surface roughness of the glass substrates was generated by chemical attack with high concentration flouridic acid vapor (HF-49%) and characterized by atomic force microscopy (AFM). The Py films were deposited by sputtering and the Ag films were deposited by resistive thermal evaporation. The hysteresis curves (M-H), obtained by optical magnetometry through the optical Kerr effect (MOKE). Through these measurements we could verify the dependence of the cohercive field Hc with surface roughness. The silver thin films, on the other hand, were characterized through timeresolved transmission measurements using the pump-probe technique with a femtosecond laser. The results of these measurements show a considerably large change in the signal amplitude and in the relaxation time of the hot electrons, as compared to the thin smooth films with the same thickness. This phenomenon is interpreted in terms of local field effects of the rough surface

ASSUNTO(S)

Ãcido fluorÃdrico histerese fisica rugosidade flouridic acid cohercive field campo coercivo campo local hysteresis local field roughness

ACESSO AO ARTIGO

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