Chromium dioxide-low temperature thin film growth, structural and physical properties

Detalhes bibliográficos
Autor(a) principal: Sousa, Pedro Miguel Fortunas Dias, 1975-
Data de Publicação: 2008
Idioma: eng
Título da fonte: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
Texto Completo: http://hdl.handle.net/10451/1562
Resumo: Tese de doutoramento em Física, apresentada à Universidade de Lisboa através da Faculdade de Ciências, 2008
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spelling Chromium dioxide-low temperature thin film growth, structural and physical propertiesFísicaTeses de doutoramento - 2008Tese de doutoramento em Física, apresentada à Universidade de Lisboa através da Faculdade de Ciências, 2008Magnetic materials exhibiting a high degree of spin polarization are being actively investigated for their potential use in spintronic devices. Among them, CrO2 is very attractive because it is a half-metal fully spin polarized at the Fermi level with a magnetic moment of 2 µB/f.u. and Curie temperature well above room temperature (RT). Therefore, much effort has been put into developing efficient and controlled methods for preparing CrO2 films which nevertherless has been a difficult task due to the CrO2 metastability. Results on the deposition of CrO2 thin films by laser-assisted Chemical Vapour Deposition (LCVD) and by Chemical Vapour Deposition (CVD) are presented in this thesis. The LCVD experiments were carried out in a high vacuum chamber at working pressures of 10-5 - 10-1 mbar and using different geometries. Films were mainly grown at RT onto sapphire substrates by photodissociation of Cr(CO)6 using a KrF excimer laser, in dynamic atmospheres containing oxygen and Argon. The structural characterization showed that some CrO2 was deposited at RT in a narrow window of experimental parameters at 0.5 mbar, although together with a significant amount of Cr2O3. Precursors partial pressures ratio and laser fluence are the prominent parameters that have to be accurately controlled in order to co-deposit both phases. A highly reproducible CVD setup consisting of a single-zone furnace with independent control of the substrate temperature was developed. CrO3 powder was used as precursor and oxygen as carrier gas. Films were grown within a broad range of deposition temperatures from 320 to 410 ºC, and O2 carrier gas flow ratesof 50 500 sccm, showing that it is viable to grow highly oriented a-axis CrO2 films at temperatures as low as 330 ºC, i.e. ~70 ºC lower than in published data for the same chemical system. Deposition parameters were correlated with the structure and microstructure, deposition kinetics, magnetic and electrical transport properties, and spin polarization of the deposited material. The growth of a Cr2O3 interfacial layer as an intrinsic feature of the deposition process is studied and discussed. Films synthesised at 330 ºC keep the high quality magnetic and transport properties as those deposited at higher temperatures.Fundação para a Ciência e a Tecnologia (FCT), (BD16567/2004)Conde, Olinda Maria Quelhas Fernandes, 1951-Silvestre, António Jorge Duarte de Castro, 1962-Repositório da Universidade de LisboaSousa, Pedro Miguel Fortunas Dias, 1975-2010-07-27T08:59:31Z20082008-01-01T00:00:00Zdoctoral thesisinfo:eu-repo/semantics/publishedVersionapplication/pdfapplication/pdftext/xmlhttp://hdl.handle.net/10451/1562enginfo:eu-repo/semantics/openAccessreponame:Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)instname:FCCN, serviços digitais da FCT – Fundação para a Ciência e a Tecnologiainstacron:RCAAP2025-03-17T12:39:33Zoai:repositorio.ulisboa.pt:10451/1562Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireinfo@rcaap.ptopendoar:https://opendoar.ac.uk/repository/71602025-05-29T02:25:05.421205Repositórios Científicos de Acesso Aberto de Portugal (RCAAP) - FCCN, serviços digitais da FCT – Fundação para a Ciência e a Tecnologiafalse
dc.title.none.fl_str_mv Chromium dioxide-low temperature thin film growth, structural and physical properties
title Chromium dioxide-low temperature thin film growth, structural and physical properties
spellingShingle Chromium dioxide-low temperature thin film growth, structural and physical properties
Sousa, Pedro Miguel Fortunas Dias, 1975-
Física
Teses de doutoramento - 2008
title_short Chromium dioxide-low temperature thin film growth, structural and physical properties
title_full Chromium dioxide-low temperature thin film growth, structural and physical properties
title_fullStr Chromium dioxide-low temperature thin film growth, structural and physical properties
title_full_unstemmed Chromium dioxide-low temperature thin film growth, structural and physical properties
title_sort Chromium dioxide-low temperature thin film growth, structural and physical properties
author Sousa, Pedro Miguel Fortunas Dias, 1975-
author_facet Sousa, Pedro Miguel Fortunas Dias, 1975-
author_role author
dc.contributor.none.fl_str_mv Conde, Olinda Maria Quelhas Fernandes, 1951-
Silvestre, António Jorge Duarte de Castro, 1962-
Repositório da Universidade de Lisboa
dc.contributor.author.fl_str_mv Sousa, Pedro Miguel Fortunas Dias, 1975-
dc.subject.por.fl_str_mv Física
Teses de doutoramento - 2008
topic Física
Teses de doutoramento - 2008
description Tese de doutoramento em Física, apresentada à Universidade de Lisboa através da Faculdade de Ciências, 2008
publishDate 2008
dc.date.none.fl_str_mv 2008
2008-01-01T00:00:00Z
2010-07-27T08:59:31Z
dc.type.driver.fl_str_mv doctoral thesis
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
status_str publishedVersion
dc.identifier.uri.fl_str_mv http://hdl.handle.net/10451/1562
url http://hdl.handle.net/10451/1562
dc.language.iso.fl_str_mv eng
language eng
dc.rights.driver.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
application/pdf
text/xml
dc.source.none.fl_str_mv reponame:Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
instname:FCCN, serviços digitais da FCT – Fundação para a Ciência e a Tecnologia
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instname_str FCCN, serviços digitais da FCT – Fundação para a Ciência e a Tecnologia
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reponame_str Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
collection Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
repository.name.fl_str_mv Repositórios Científicos de Acesso Aberto de Portugal (RCAAP) - FCCN, serviços digitais da FCT – Fundação para a Ciência e a Tecnologia
repository.mail.fl_str_mv info@rcaap.pt
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