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Habilitation Thesis
DOI
10.11606/T.43.2015.tde-31072015-161455
Document
Author
Full name
Hercilio Rodolfo Rechenberg
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 1979
Committee
Oliveira Junior, Nei Fernandes de (President)
Barros, Fernando de Souza
Cattani, Mauro Sergio Dorsa
Gazzinelli, Ramayana
Silva Filho, Roberto Leal Lobo e
Title in Portuguese
Propriedades magnéticas dos vidros de spins não-metálicos CoO."Al IND.2""O IND3""SiO IND.2" e MnO."Al IND.2" "O IND.3" "SiO IND.2"
Keywords in Portuguese
Campo magnético
Magnetismo
Matéria condensada
Abstract in Portuguese
Efetuamos medidas de magnetização e de suscetibilidade de em vidros CoO-A-t2o 3 .sio2 e MnO.A!2o 3 .sio2 , na presença de campos magnéticos estáticos. Os resultados foram analisados em termos de um modelo proposto. por de Graaf et al. , que supõe a existência em baixas temperaturas de domínios antiferromagnéticos com características do superparamagnetismo de Néel. As medidas em campos elevados (até 60 kG), tanto de magnetização como de suscetibilidade, revelaram a existência de um termo constante na suscetibilidade, que atribuimos ao antiferromagnetismo dos domínios. A variação da suscetibilidade em função do campo, para campos da ordem de 100 G, apresenta um pico na região de tem peraturas em que a suscetibilidade inicial também apresenta um pico. Mostramos que esse resultado é consistente com o modelo de domínios. Dessas mesmas medidas deduzimos o momento efetivo médio dos domínios ("-' 100 llB) , e observamos que esse momento é função decrescente da temperatura.
Title in English
Magnetic properties of glasses of non-metallic spins CoO. "Al IND.2" "The IND3" "SiO IND.2" and MnO. "Al IND.2" "The IND.3" "SiO IND.2"
Keywords in English
Condensed Matter
Magnetic field Magnetism
Abstract in English
We have performed magnetization measurements and susceptibility The CoO-on-glass t2o .sio2 and MnO.A 3! 2 3 .sio2 in the presence of static magnetic fields. The results were analyzed in terms of a model proposed. by de Graaff et al. Which supposes the existence in low temperature antiferromagnetic domains with superparamagnetism features of Neel. The measures at high fields (up to 60 kg), both magnetization and susceptibility, revealed the existence of a constant term in the susceptibility, we attach the antiferromagnetic domains. The variation in susceptibility as a function of the field, 100 G field of order, displays a peak in the region has temperatures wherein the initial susceptibility also provides a peak. We show that this result is consistent with the model domain. Those measures deduce the average effective time of the domains ('-' 100 LLB), and observed that that moment is decreasing function of temperature.
 
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Rechenberg.pdf (3.53 Mbytes)
Publishing Date
2015-08-13
 
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