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The unoccupied electronic structure of the semi-conducting room temperature molecular magnet V(TCNE)2
Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
2008 (English)In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 452, no 1-3, 173-177 p.Article in journal (Refereed) Published
Abstract [en]

The unoccupied electronic structure of the organic-based magnet V(TCNE)x (TCNE = tetracyanoethylene, x~2) has been studied with near edge x-ray absorption fine structure (NEXAFS) and with photoelectron spectroscopy (PES). By studying V(TCNE)x upon sodium-doping, the electron-accepting state, i.e. the lowest unoccupied molecular orbital (LUMO) of V(TCNE)x was shown mainly to be localized on (TCNE)--units in contrast to the hole-accepting state, i.e. the highest occupied molecular orbital (HOMO), which previously was assigned primarily to be V(3d)-derived. This study also showed that there are trap states for electron transport located below the (TCNE)2- level, likely leading to decreased electron mobility.

Place, publisher, year, edition, pages
Institutionen för teknik och naturvetenskap , 2008. Vol. 452, no 1-3, 173-177 p.
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:liu:diva-11143DOI: 10.1016/j.cplett.2007.12.049OAI: oai:DiVA.org:liu-11143DiVA: diva2:17583
Note
Original publication: Elin Carlegrim, Anna Kanciurzewska, Michel P. de Jong, Carl Tengstedt and Mats Fahlman, The unoccupied electronic structure of the semi-conducting room temperature molecular magnet V(TCNE)2, 2008, Chemical Physics Letters, (452), 1-3, 173-177. http://dx.doi.org/10.1016/j.cplett.2007.12.049. Copyright: Elsevier Ltd, http://www.elsevier.com/Available from: 2008-02-27 Created: 2008-02-27 Last updated: 2017-12-13
In thesis
1. Preparation and characterization of an organic-based magnet
Open this publication in new window or tab >>Preparation and characterization of an organic-based magnet
2007 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

In the growing field of spintronics there is a strong need for development of flexible lightweight semi-conducting magnets. Molecular organic-based magnets are attractive candidates since it is possible to tune their properties by organic chemistry, making them so-called “designer magnets”. Vanadium tetracyanoethylene, V(TCNE)x, is particularly interesting since it is a semiconductor with Curie temperature above room temperature (TC~400 K). The main problem with these organic-based magnets is that they are extremely air sensitive. This thesis reports on the frontier electronic structure of the V(TCNE)x by characterization with photoelectron spectroscopy (PES) and near edge x-ray absorption fine structure (NEXAFS) spectroscopy. It also presents a new and more flexible preparation method of this class of organic-based thin film magnets. The result shows improved air stability of the V(TCNE)x prepared with this method as compared to V(TCNE)x prepared by hitherto used methods.

Place, publisher, year, edition, pages
Institutionen för teknik och naturvetenskap, 2007. 32 p.
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1338
Keyword
Organic-based magnets, spintronics, photoelectron spectroscopy, near edge x-ray absorption fine structure spectroscopy, chemical vapor deposition, physical vapor deposition
National Category
Other Engineering and Technologies not elsewhere specified
Identifiers
urn:nbn:se:liu:diva-10426 (URN)978-91-85895-21-2 (ISBN)
Presentation
2007-12-07, Jordan-Fermi, Fysikhuset, Campus Valla, Linköpings universitet, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2008-01-07 Created: 2008-01-07 Last updated: 2009-04-09
2. Development of Organic-Based Thin Film Magnets for Spintronics
Open this publication in new window or tab >>Development of Organic-Based Thin Film Magnets for Spintronics
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In the growing field of spintronics, development of semiconducting magnets is a high priority. Organic-based molecular magnets are attractive candidates since their properties can be tailor-made by organic chemistry. Other advantages include low weight and low temperature processing. Vanadium tetracyanoethylene, V(TCNE)x, x~2, is particularly interesting since it is one of very few semiconducting magnets with magnetic ordering above room temperature.

The aim of the research presented in this thesis was to prepare and characterize thin film organic-based magnets with focus on V(TCNE)x. Photoelectron and absorption spectroscopy studies were performed leading to a more complete picture of the electronic and chemical structure of the material. Depending on the preparation method of V(TCNE)x, the material contains varying amounts of disorder which among other things makes it very air sensitive. In this thesis, a new preparation method for organic-based magnets based on physical vapor deposition is presented and the first result shows that it generates less air sensitive V(TCNE)x than previous methods reported. A new spin valve design based on V(TCNE)x was proposed where the material delivers both spin-filtering and spin-transporting functionality, making use of its fully spin-polarized transport levels. In such devices, the interface of V(TCNE)x with ferromagnetic metals is of great importance and was hence studied. As vanadium ions always are very reactive towards oxygen, substituting vanadium by a less reactive ion would be desirable from both an interface engineering and device packaging perspective. Very few alternatives exist however that orders magnetically above room temperature. In order to find out what are the key design criteria for preparing thin film semiconducting room temperature magnets, we have begun to study systems which order magnetically much below room temperature and compared them with V(TCNE)x.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2010. 49 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1317
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-56262 (URN)978-91-7393-385-8 (ISBN)
Public defence
2010-05-25, Planck, Fysikhuset, Campus Valla, Linköpings universitet, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2010-05-05 Created: 2010-05-05 Last updated: 2010-05-05Bibliographically approved

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