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Master's Dissertation
DOI
10.11606/D.43.2008.tde-29082008-103327
Document
Author
Full name
Leonardo Alonso
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2008
Supervisor
Committee
Cornejo, Daniel Reinaldo (President)
Missell, Frank Patrick
Sipahi, Guilherme Matos
Title in Portuguese
Modelo de Preisach e análise FORC aplicados a filmes com exchange-bias
Keywords in Portuguese
Antiferromagnetismo
Ferromagnetismo
Filmes finos
Magnetismo
Spin
Abstract in Portuguese
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.
Title in English
Preisach model and Forc analysis applied to exchang biased films
Keywords in English
Antiferromagnetism
Coercivity
Exchanged bias
Ferromagnetism
Forc
Hysteresis
Magnetism
Preisach
Spin
Thin films
Abstract in English
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)
Publishing Date
2008-09-16
 
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