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Mémoire de Maîtrise
DOI
10.11606/D.43.2008.tde-29082008-103327
Document
Auteur
Nom complet
Leonardo Alonso
Adresse Mail
Unité de l'USP
Domain de Connaissance
Date de Soutenance
Editeur
São Paulo, 2008
Directeur
Jury
Cornejo, Daniel Reinaldo (Président)
Missell, Frank Patrick
Sipahi, Guilherme Matos
Titre en portugais
Modelo de Preisach e análise FORC aplicados a filmes com exchange-bias
Mots-clés en portugais
Antiferromagnetismo
Ferromagnetismo
Filmes finos
Magnetismo
Spin
Resumé en portugais
Neste trabalho foram produzidos filmes finos de Si[100]/buffer/NiFe/FeMn/Ta (buffer = Cu; Ta) e válvulas de spin de Si[100]/Cu/NiFe/Cu/NiFe/FeMn/Ta via Sputtering, e seus comportamentos magnéticos foram estudados analisando curvas de inversão de primeira ordem (First Order Reversal Curves, FORCs). Um Modelo de Preisach com Exchange-Bias foi desenvolvido e sua implementação computacional permitiu simular a histerese e as curvas forcas das bicamadas de NiFe/FeMn. O modelo também permitiu reproduzir os comportamentos assimétricos dos dois ramos da curva de histerese destes filmes. A análise dos resultados evidenciou os efeitos de campo médio sobre a camada de Py em função da espessura da camada de FeMn. A aplicação da análise FORC nas válvulas de spin se revelou interessante para estudar o grau de acoplamento entre as camadas livre e pressa, assim como os efeitos de campo médio em cada camada.
Titre en anglais
Preisach model and Forc analysis applied to exchang biased films
Mots-clés en anglais
Antiferromagnetism
Coercivity
Exchanged bias
Ferromagnetism
Forc
Hysteresis
Magnetism
Preisach
Spin
Thin films
Resumé en anglais
In this work, thin films of Si[100]/buffer/NiFe/FeMn/Ta (buffer = Cu; Ta) and spin valves of Si[100]/Cu/NiFe/Cu/NiFe/FeMn/Ta were produced via sputtering and their magnetic behavior were studied by First Order Reversal Curves (FORC's) analysis. A Preisach Model with Exchange-Bias was developed and applied in order to simulate the hysteresis and the first order reversal curves of the NiFe/FeMn bilayers. In addition, the model allowed to reproduce the asymmetric behaviors present in both branches of the hysteresis curve in these films. The study put in evidence the mean field effects on de Py layer as a function of the thickness of the FeMn layer. The application of the FORC analysis in the spin valves was interesting to study the degree of coupling between the free and the pressed layers, as well as the effect of mean field in each layer.
 
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DissAlonso.pdf (3.17 Mbytes)
Date de Publication
2008-09-16
 
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