Ferromagnetism in (Ga,Mn)As and (Ga,Mn)N

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.author Raebiger, Hannes
dc.date.accessioned 2012-02-17T07:38:10Z
dc.date.available 2012-02-17T07:38:10Z
dc.date.issued 2006-04-21
dc.identifier.isbn 951-22-8122-8
dc.identifier.issn 1455-1802
dc.identifier.uri https://aaltodoc.aalto.fi/handle/123456789/2687
dc.description.abstract (Ga,Mn)As and (Ga,Mn)N are so called diluted magnetic semiconductors, i.e. semiconductor based materials made ferromagnetic by inclusion of a magnetic element—in this case Mn. This type of materials bridge over the incompatibilities in metal–semiconductor interfaces in electronics components and have an enormous potential for future spintronics applications, where both charge and spin degrees of freedom can be employed simultaneously. In order to design new—or employ the existing—diluted magnetic semiconductor materials, the underlying mechanisms of magnetism must be understood. In this work a theoretical study of the structural and magnetic properties of the two most important prototype materials, (Ga,Mn)As and (Ga,Mn)N, is presented. Ferromagnetism arises from the quantum mechanical exchange interactions, but is by its very nature a macroscopic ordering effect. Therefore a multiscale approach is employed, beginning from quantum mechanical interactions. Both microscopic configurational energies and corresponding magnetic interactions are calculated from first principles. These energies are used in Monte Carlo simulations to study macroscopic and finite temperature properties. Curie temperatures are estimated using the Weiss molecular field theory, as well as a more sophisticated Monte Carlo approach. We show that both (Ga,Mn)As and (Ga,Mn)N consist largely of Mn clusters, and that the electronic and magnetic properties of these clusters differ significantly from those of single substitutional impurities. For (Ga,Mn)As we also show using lattice kinetic Monte Carlo methods that clustering occurs during growth and annealing via the Ga monovacancy mediated diffusion. For both materials clustering efficiently reduces the Curie temperatures even though the underlying band structure trends are different. The Curie temperatures are estimated for (Ga,Mn)As using the Weiss molecular field theory, while for (Ga,Mn)N we employ Monte Carlo methods in order to obtain the Curie temperatures. en
dc.format.extent 48, [35]
dc.format.mimetype application/pdf
dc.language.iso en en
dc.publisher Helsinki University of Technology en
dc.publisher Teknillinen korkeakoulu fi
dc.relation.ispartofseries Dissertation / Laboratory of Physics, Helsinki University of Technology en
dc.relation.ispartofseries 139 en
dc.relation.haspart H. Raebiger, A. Ayuela, and R. M. Nieminen, Intrinsic hole localization mechanism in magnetic semiconductors, Journal of Physics: Condensed Matter 16, L457-L462 (2004). [article1.pdf] © 2004 Institute of Physics Publishing. By permission.
dc.relation.haspart H. Raebiger, A. Ayuela, J. von Boehm, and R. M. Nieminen, Clustering of Mn in (Ga,Mn)As, Journal of Magnetism and Magnetic Materials 290-291, 1398-1401 (2005). [article2.pdf] © 2005 Elsevier Science. By permission.
dc.relation.haspart H. Raebiger, T. Hynninen, A. Ayuela, and J. von Boehm, Effects of Mn clustering on ferromagnetism in (Ga,Mn)As, Physica B, in press, 4 pages. [article3.pdf] © 2006 Elsevier Science. By permission.
dc.relation.haspart H. Raebiger, A. Ayuela, and J. von Boehm, Electronic and magnetic properties of substitutional Mn clusters in (Ga,Mn)As, Physical Review B 72, 014465, 7 pages (2005). [article4.pdf] © 2005 American Physical Society. By permission.
dc.relation.haspart H. Raebiger, M. G. Ganchenkova, and J. von Boehm, Diffusion and clustering of substitutional Mn in (Ga,Mn)As, cond-mat/0603135, 4 pages, submitted for publication.
dc.relation.haspart T. Hynninen, H. Raebiger, A. Ayuela, and J. von Boehm, High Curie temperatures in (Ga,Mn)N from Mn clustering, Applied Physics Letters 88, 122501, 3 pages (2006). [article6.pdf] © 2006 American Institute of Physics. By permission.
dc.relation.haspart T. Hynninen, H. Raebiger, and J. von Boehm, A multiscale study of ferromagnetism in clustered (Ga,Mn)N, Journal of Physics: Condensed Matter 18, 1561-1567 (2006). [article7.pdf] © 2006 Institute of Physics Publishing. By permission.
dc.subject.other Physics en
dc.title Ferromagnetism in (Ga,Mn)As and (Ga,Mn)N en
dc.type G5 Artikkeliväitöskirja fi
dc.description.version reviewed en
dc.contributor.department Department of Engineering Physics and Mathematics en
dc.contributor.department Teknillisen fysiikan ja matematiikan osasto fi
dc.subject.keyword diluted magnetic semiconductors en
dc.subject.keyword clustering en
dc.subject.keyword Curie temperature en
dc.subject.keyword density-functional calculation en
dc.identifier.urn urn:nbn:fi:tkk-006746
dc.type.dcmitype text en
dc.type.ontasot Väitöskirja (artikkeli) fi
dc.type.ontasot Doctoral dissertation (article-based) en
dc.contributor.lab Laboratory of Physics en
dc.contributor.lab Fysiikan laboratorio fi


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