| Ferromagnetic interactions in hosted bipartite materials-generalized-double-exchange and generalized-superexchange interactions. | |
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MedLine Citation:
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PMID: 21411907 Owner: NLM Status: In-Data-Review |
Abstract/OtherAbstract:
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Defect-induced magnetism in dilute magnetic semiconductors challenges our understanding of magnetism in solids. Theories based on conventional superexchange or double-exchange interactions cannot explain long range magnetic order at concentrations below the percolation threshold in these materials. On the other hand, the codoping-induced magnetism, which can explain magnetic interactions below the percolation threshold, has eluded explanation. In this work we propose that defect-induced magnetism in codoped non-magnetic materials can be viewed within a molecular generalization of the atomic double-exchange and superexchange interactions applied to an arbitrary bipartite lattice hosted by (or embedded in) defect-free non-magnetic materials. In this view, the crucial factor for the development of magnetism appears to be the defect complementarity of the codopants. We demonstrate this by taking ZnO and GaN (the most widely studied doped oxide and nitride magnetic semiconductors, respectively) as host materials and perform theoretical calculations using ab initio methods after codoping them with transition metal impurities for a variety of configurations. Our results indicate that the magnetic coupling among the induced and/or doped magnetic moments takes the form of an interaction among spin-polarized molecular units which is facilitated by the formation of the hosted bipartite codopant structures. The universality of the proposed mechanism is further supported by earlier results referring to the rhombohedral C(60)-based polymers. |
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Authors:
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Antonis N Andriotis; Sergey Lisenkov; Madhu Menon |
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Publication Detail:
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Type: Journal Article Date: 2011-02-09 |
Journal Detail:
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Title: Journal of physics. Condensed matter : an Institute of Physics journal Volume: 23 ISSN: 0953-8984 ISO Abbreviation: J Phys Condens Matter Publication Date: 2011 Mar |
Date Detail:
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Created Date: 2011-03-17 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 101165248 Medline TA: J Phys Condens Matter Country: England |
Other Details:
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Languages: eng Pagination: 086004 Citation Subset: IM |
Affiliation:
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Institute of Electronic Structure and Laser, FORTH, PO Box 1527, 71110 Heraklio, Crete, Greece. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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