Half-metal: Difference between revisions
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A '''half-metal''' is any substance that acts as a [[Electrical conductor|conductor]] to [[electron]]s of one [[spin (physics)|spin]] orientation, but as an [[Electrical insulation|insulator]] to those of the opposite orientation. |
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[[Image:Half metar sattar.JPG|thumb|The electronic structure of a half-metal. <math>E_f</math> is the [[Fermi level]], <math>N(E)</math> is the [[density of states]] for spin down (on the left) and spin up (on the right). In this case, the half-metal is conducting in the minority spin channel.]] |
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A '''half-metal''' is any substance that acts as a [[Electrical conductor|conductor]] to [[electron]]s of one [[Spin (physics)|spin]] orientation, but as an [[Electrical insulation|insulator]] or [[semiconductor]] to those of the opposite orientation. Although all half-metals are [[Ferromagnetism|ferromagnetic]] (or [[Ferrimagnetism|ferrimagnetic]]), most ferromagnets are not half-metals. Many of the known examples of half-metals are [[oxide]]s, [[sulfide]]s, or [[Heusler alloy]]s.<ref name=COEY02>{{cite journal |first1=J.M.D. |last1=Coey |first2=M.|last2=Venkatesan|year=2002 |title=Half-metallic ferromagnetism: Example of CrO2 |journal=Journal of Applied Physics |volume=91 |issue=10 |pages=8345–50 |doi=10.1063/1.1447879 |bibcode = 2002JAP....91.8345C}}</ref> Types of half-metallic compounds theoretically predicted so far include some Heusler alloys, such as {{chem2|Co2FeSi}}, NiMnSb, and PtMnSb; some Si-containing half–Heusler alloys with Curie temperatures over 600 K, such as NiCrSi and PdCrSi; some transition-metal oxides, including rutile structured {{chem2|CrO2}}; some perovskites, such as {{chem2|LaMnO3}} and {{chem2|SeMnO3}}; and a few more simply structured zincblende (ZB) compounds, including CrAs and superlattices. NiMnSb and {{chem2|CrO2}} have been experimentally determined to be half-metals at very low temperatures. |
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Conduction in magnetic materials is due to two types of electron, i.e., electrons with spin up and electrons with spin down.<ref>A. Fert and I.A Campbell, Phys. Rev. Lett. 21, 1190 (1968)</ref> |
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In half-metals, the valence band for one spin orientation is partially filled while there is a gap in the density of states for the other spin orientation. This results in conducting behavior for only electrons in the first spin orientation. In some half-metals, the majority spin channel is the conducting one while in others the minority channel is.<ref>{{Cite journal |last=Rostami |first=Mohammad |last2=Afkani |first2=Mohammad |last3=Torkamani |first3=Mohammad Reza |last4=Kanjouri |first4=Faramarz |date=2020-07-01 |title=Bulk and surface DFT investigations of the electronic and magnetic properties of CsXNO (X = Mg, Ca and Sr) quaternary Heusler alloys |url=https://www.sciencedirect.com/science/article/pii/S0254058420302996 |journal=Materials Chemistry and Physics |volume=248 |pages=122923 |doi=10.1016/j.matchemphys.2020.122923 |issn=0254-0584}}</ref> |
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In half-metals, the valence band related to one type of these electrons is fully filled and the other is partially filled. So only one type of electrons (the spin type with the partially filled band) can pass through it, because full bands have a net conductance of zero. |
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Half-metals were first described in 1983, as an explanation for the electrical properties of [[manganese]]-based [[Heusler alloy]]s.<ref>{{cite journal |last1=de Groot |first1=R. A. |last2=Mueller |first2=F. M. |last3=Engen |first3=P. G. van |last4=Buschow |first4=K. H. J. |title=New Class of Materials: Half-Metallic Ferromagnets |journal=Physical Review Letters |date=20 June 1983 |volume=50 |issue=25 |pages=2024–2027 |doi=10.1103/PhysRevLett.50.2024 |bibcode=1983PhRvL..50.2024D |url=https://pure.rug.nl/ws/files/3419075/1983PhysRevLettdeGroot.pdf |hdl=11370/e3946f6b-8acb-4e0a-80cf-735506203f25 |hdl-access=free}}</ref> |
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A schematic diagram of the band structure of a half-metal is shown below. |
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[[Image:Half metar sattar.JPG]] |
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Some notable half-metals are [[chromium(IV) oxide]] |
Some notable half-metals are [[chromium(IV) oxide]], [[magnetite]], and [[lanthanum strontium manganite]] (LSMO),<ref name=COEY02/> as well as [[chromium arsenide]]. Half-metals have attracted some interest for their potential use in [[spintronics]]. |
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==See also== |
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*[[Antiferromagnetism]] |
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*[[Semimetal]] |
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==References== |
==References== |
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{{Reflist}} |
{{Reflist}} |
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*''Nature'' 444, xiii - xiii (16 Nov 2006) |
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==Further reading== |
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* http://www-users.york.ac.uk/~ah566/research/half_metals.html |
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*{{cite journal |doi=10.1016/j.jmmm.2016.04.056 |title=Electronic, magnetic and thermal properties of Co2CrxFe1−xX (X=Al, Si) Heusler alloys: First-principles calculations |journal=Journal of Magnetism and Magnetic Materials |volume=414 |pages=219–26 |year=2016 |last1=Guezlane |first1=M |last2=Baaziz |first2=H |last3=El Haj Hassan |first3=F |last4=Charifi |first4=Z |last5=Djaballah |first5=Y |bibcode=2016JMMM..414..219G}} |
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*{{cite journal |doi=10.1038/nature05180 |pmid=17108960 |title=Half-metallic graphene nanoribbons |journal=Nature |volume=444 |issue=7117 |pages=347–9 |year=2006 |last1=Son |first1=Young-Woo |last2=Cohen |first2=Marvin L |last3=Louie |first3=Steven G |bibcode=2006Natur.444..347S |arxiv=cond-mat/0611600 |s2cid=52851642}} |
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* http://www-users.york.ac.uk/~ah566/research/half_metals.html{{full citation needed|date=January 2018}}{{Dead link|date=January 2020 |bot=InternetArchiveBot |fix-attempted=yes}} |
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Latest revision as of 14:30, 24 January 2024
A half-metal is any substance that acts as a conductor to electrons of one spin orientation, but as an insulator or semiconductor to those of the opposite orientation. Although all half-metals are ferromagnetic (or ferrimagnetic), most ferromagnets are not half-metals. Many of the known examples of half-metals are oxides, sulfides, or Heusler alloys.[1] Types of half-metallic compounds theoretically predicted so far include some Heusler alloys, such as Co2FeSi, NiMnSb, and PtMnSb; some Si-containing half–Heusler alloys with Curie temperatures over 600 K, such as NiCrSi and PdCrSi; some transition-metal oxides, including rutile structured CrO2; some perovskites, such as LaMnO3 and SeMnO3; and a few more simply structured zincblende (ZB) compounds, including CrAs and superlattices. NiMnSb and CrO2 have been experimentally determined to be half-metals at very low temperatures.
In half-metals, the valence band for one spin orientation is partially filled while there is a gap in the density of states for the other spin orientation. This results in conducting behavior for only electrons in the first spin orientation. In some half-metals, the majority spin channel is the conducting one while in others the minority channel is.[2]
Half-metals were first described in 1983, as an explanation for the electrical properties of manganese-based Heusler alloys.[3]
Some notable half-metals are chromium(IV) oxide, magnetite, and lanthanum strontium manganite (LSMO),[1] as well as chromium arsenide. Half-metals have attracted some interest for their potential use in spintronics.
References
[edit]- ^ a b Coey, J.M.D.; Venkatesan, M. (2002). "Half-metallic ferromagnetism: Example of CrO2". Journal of Applied Physics. 91 (10): 8345–50. Bibcode:2002JAP....91.8345C. doi:10.1063/1.1447879.
- ^ Rostami, Mohammad; Afkani, Mohammad; Torkamani, Mohammad Reza; Kanjouri, Faramarz (2020-07-01). "Bulk and surface DFT investigations of the electronic and magnetic properties of CsXNO (X = Mg, Ca and Sr) quaternary Heusler alloys". Materials Chemistry and Physics. 248: 122923. doi:10.1016/j.matchemphys.2020.122923. ISSN 0254-0584.
- ^ de Groot, R. A.; Mueller, F. M.; Engen, P. G. van; Buschow, K. H. J. (20 June 1983). "New Class of Materials: Half-Metallic Ferromagnets" (PDF). Physical Review Letters. 50 (25): 2024–2027. Bibcode:1983PhRvL..50.2024D. doi:10.1103/PhysRevLett.50.2024. hdl:11370/e3946f6b-8acb-4e0a-80cf-735506203f25.
Further reading
[edit]- Guezlane, M; Baaziz, H; El Haj Hassan, F; Charifi, Z; Djaballah, Y (2016). "Electronic, magnetic and thermal properties of Co2CrxFe1−xX (X=Al, Si) Heusler alloys: First-principles calculations". Journal of Magnetism and Magnetic Materials. 414: 219–26. Bibcode:2016JMMM..414..219G. doi:10.1016/j.jmmm.2016.04.056.
- Son, Young-Woo; Cohen, Marvin L; Louie, Steven G (2006). "Half-metallic graphene nanoribbons". Nature. 444 (7117): 347–9. arXiv:cond-mat/0611600. Bibcode:2006Natur.444..347S. doi:10.1038/nature05180. PMID 17108960. S2CID 52851642.
- http://www-users.york.ac.uk/~ah566/research/half_metals.html[full citation needed][permanent dead link]
- http://www.tcd.ie/Physics/People/Michael.Coey/oxsen/newsletter/january98/halfmeta.htm[full citation needed]
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