Magnetic and transport properties of diluted granular multilayers

Detalhes bibliográficos
Autor(a) principal: Silva, Hugo G.
Data de Publicação: 2009
Outros Autores: Gomes, Henrique L., Pogorelov, Y. G., Pereira, L. M. C., Kakazei, G. N., Sousa, J. B., Araújo, J. P., Mariano, José F. M. L., Cardoso, S., Freitas, P. P.
Tipo de documento: Artigo
Idioma: eng
Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
Texto Completo: http://hdl.handle.net/10400.1/3283
Resumo: The magnetic and transport properties of Co80Fe20t /Al2O34 nm multilayers with low nominal thicknesses t=0.7 and 0.9 nm of Co80Fe20 granular layers are studied. Magnetic studies find a superparamagnetic state above the blocking temperature Tb of field-cooled/zero-field-cooled splitting that grows with t and decreases with H. The low-voltage Ohmic tunnel transport passes to non-Ohmic IV3/2 law for applied fields above 500 V/cm. At fixed V, the temperature dependence of conductance reveals an anomalous dip around 220 K, which can be attributed to the effect of surface contamination by supercooled water. Current-in-plane tunnel magnetoresistance MR ratio tends, at lower t, to higher maximum values 8% at room temperature but to lower field sensitivity. This may indicate growing discorrelation effect e.g., between shrinking areas of correlated moments in this regime and corroborates the deficit of granule magnetization estimated from the Inoue–Maekawa MR fit, compared to that from direct magnetization measurements. MR displays a mean-field-like critical behavior when t approaches the point of superparamagnetic/ superferromagnetic transition tc1.3 nm at room temperature from below, different from the formerly reported percolationlike behavior at approaching it from above.With growing temperature, MR reveals, beyond the common decrease, an anomalous plateau from Tb30–50 K up to some higher value T150–200 K, not seen at higher t.
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spelling Magnetic and transport properties of diluted granular multilayersThe magnetic and transport properties of Co80Fe20t /Al2O34 nm multilayers with low nominal thicknesses t=0.7 and 0.9 nm of Co80Fe20 granular layers are studied. Magnetic studies find a superparamagnetic state above the blocking temperature Tb of field-cooled/zero-field-cooled splitting that grows with t and decreases with H. The low-voltage Ohmic tunnel transport passes to non-Ohmic IV3/2 law for applied fields above 500 V/cm. At fixed V, the temperature dependence of conductance reveals an anomalous dip around 220 K, which can be attributed to the effect of surface contamination by supercooled water. Current-in-plane tunnel magnetoresistance MR ratio tends, at lower t, to higher maximum values 8% at room temperature but to lower field sensitivity. This may indicate growing discorrelation effect e.g., between shrinking areas of correlated moments in this regime and corroborates the deficit of granule magnetization estimated from the Inoue–Maekawa MR fit, compared to that from direct magnetization measurements. MR displays a mean-field-like critical behavior when t approaches the point of superparamagnetic/ superferromagnetic transition tc1.3 nm at room temperature from below, different from the formerly reported percolationlike behavior at approaching it from above.With growing temperature, MR reveals, beyond the common decrease, an anomalous plateau from Tb30–50 K up to some higher value T150–200 K, not seen at higher t.American Institute of PhysicsSapientiaSilva, Hugo G.Gomes, Henrique L.Pogorelov, Y. G.Pereira, L. M. C.Kakazei, G. N.Sousa, J. B.Araújo, J. P.Mariano, José F. M. L.Cardoso, S.Freitas, P. P.2014-01-07T11:09:42Z20092014-01-02T18:32:46Z2009-01-01T00:00:00Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articleapplication/pdfhttp://hdl.handle.net/10400.1/3283engSilva, H. G.; Gomes, H. L.; Pogorelov, Y. G.; Pereira, L. M. C.; Kakazei, G. N.; Sousa, J. B.; Araújo, J. P.; Mariano, J. F. L.; Cardoso, S.; Freitas, P. P. Magnetic and transport properties of diluted granular multilayers, Journal of Applied Physics, 106, 11, 113910-113917, 2009.0021-8979AUT: HGO00803;http://dx.doi.org/10.1063/1.3266010info:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2023-07-24T10:14:19Zoai:sapientia.ualg.pt:10400.1/3283Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-19T19:56:53.197257Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse
dc.title.none.fl_str_mv Magnetic and transport properties of diluted granular multilayers
title Magnetic and transport properties of diluted granular multilayers
spellingShingle Magnetic and transport properties of diluted granular multilayers
Silva, Hugo G.
title_short Magnetic and transport properties of diluted granular multilayers
title_full Magnetic and transport properties of diluted granular multilayers
title_fullStr Magnetic and transport properties of diluted granular multilayers
title_full_unstemmed Magnetic and transport properties of diluted granular multilayers
title_sort Magnetic and transport properties of diluted granular multilayers
author Silva, Hugo G.
author_facet Silva, Hugo G.
Gomes, Henrique L.
Pogorelov, Y. G.
Pereira, L. M. C.
Kakazei, G. N.
Sousa, J. B.
Araújo, J. P.
Mariano, José F. M. L.
Cardoso, S.
Freitas, P. P.
author_role author
author2 Gomes, Henrique L.
Pogorelov, Y. G.
Pereira, L. M. C.
Kakazei, G. N.
Sousa, J. B.
Araújo, J. P.
Mariano, José F. M. L.
Cardoso, S.
Freitas, P. P.
author2_role author
author
author
author
author
author
author
author
author
dc.contributor.none.fl_str_mv Sapientia
dc.contributor.author.fl_str_mv Silva, Hugo G.
Gomes, Henrique L.
Pogorelov, Y. G.
Pereira, L. M. C.
Kakazei, G. N.
Sousa, J. B.
Araújo, J. P.
Mariano, José F. M. L.
Cardoso, S.
Freitas, P. P.
description The magnetic and transport properties of Co80Fe20t /Al2O34 nm multilayers with low nominal thicknesses t=0.7 and 0.9 nm of Co80Fe20 granular layers are studied. Magnetic studies find a superparamagnetic state above the blocking temperature Tb of field-cooled/zero-field-cooled splitting that grows with t and decreases with H. The low-voltage Ohmic tunnel transport passes to non-Ohmic IV3/2 law for applied fields above 500 V/cm. At fixed V, the temperature dependence of conductance reveals an anomalous dip around 220 K, which can be attributed to the effect of surface contamination by supercooled water. Current-in-plane tunnel magnetoresistance MR ratio tends, at lower t, to higher maximum values 8% at room temperature but to lower field sensitivity. This may indicate growing discorrelation effect e.g., between shrinking areas of correlated moments in this regime and corroborates the deficit of granule magnetization estimated from the Inoue–Maekawa MR fit, compared to that from direct magnetization measurements. MR displays a mean-field-like critical behavior when t approaches the point of superparamagnetic/ superferromagnetic transition tc1.3 nm at room temperature from below, different from the formerly reported percolationlike behavior at approaching it from above.With growing temperature, MR reveals, beyond the common decrease, an anomalous plateau from Tb30–50 K up to some higher value T150–200 K, not seen at higher t.
publishDate 2009
dc.date.none.fl_str_mv 2009
2009-01-01T00:00:00Z
2014-01-07T11:09:42Z
2014-01-02T18:32:46Z
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
dc.type.driver.fl_str_mv info:eu-repo/semantics/article
format article
status_str publishedVersion
dc.identifier.uri.fl_str_mv http://hdl.handle.net/10400.1/3283
url http://hdl.handle.net/10400.1/3283
dc.language.iso.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv Silva, H. G.; Gomes, H. L.; Pogorelov, Y. G.; Pereira, L. M. C.; Kakazei, G. N.; Sousa, J. B.; Araújo, J. P.; Mariano, J. F. L.; Cardoso, S.; Freitas, P. P. Magnetic and transport properties of diluted granular multilayers, Journal of Applied Physics, 106, 11, 113910-113917, 2009.
0021-8979
AUT: HGO00803;
http://dx.doi.org/10.1063/1.3266010
dc.rights.driver.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv American Institute of Physics
publisher.none.fl_str_mv American Institute of Physics
dc.source.none.fl_str_mv reponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
instacron:RCAAP
instname_str Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
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institution RCAAP
reponame_str Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
collection Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
repository.name.fl_str_mv Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
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