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Article: Quantum coherence effect in spin-polarized transport through nano-magnets

TitleQuantum coherence effect in spin-polarized transport through nano-magnets
Authors
Issue Date2008
PublisherInstitute of Physics Publishing. The Journal's web site is located at http://www.iop.org/Journals/jpcm
Citation
Journal Of Physics Condensed Matter, 2008, v. 20 n. 41 How to Cite?
AbstractUsing a simplified toy model, we study the quantum coherence effect in the spin-polarized transport of nano-magnets. A density matrix master equation is used to describe the correlation in the magnet. Through comparison with the classical rate equation, the coherence effect is clearly demonstrated. We find that the interaction between the spin-polarized current and the nano-magnet can be tuned by changing the bias voltage. At small bias voltage, the ferromagnetic lead will induce an antiferromagnetic exchange field. This exchange field is raised from the dynamics of the nondiagonal reduced density matrix elements of the nano-magnet. It is an obvious coherence effect and is beyond the scope of the classical rate equation. When bias voltage increases, tunneling becomes important and the dominating spin control mechanism is the spin accumulation which has been well studied in recent works (Timm and Elste 2006 Phys. Rev. B 73 235304, Timm 2007 Phys. Rev. B 76 014421, Misiorny and Barnas 2007 Phys. Rev. B 76 054448, Barnas et al 2000 Phys. Rev. B 62 12363). Our results obviously imply that the coherence effect in the spin-polarized transport of the nano-magnet cannot be ignored even in the collinear structure. This phenomenon is quite different from the case of the quantum dot (QD) spin valve which means that the classical rate equation, which is widely used in the study of the QD spin valve, is invalid for the nano-magnet-based spin valve. A density matrix description becomes essential. Our results are helpful for future investigations of nano-magnet devices. © 2008 IOP Publishing Ltd.
Persistent Identifierhttp://hdl.handle.net/10722/175155
ISSN
2015 Impact Factor: 2.209
2015 SCImago Journal Rankings: 0.812
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorGao, Jen_US
dc.contributor.authorSun, Qen_US
dc.contributor.authorXie, XCen_US
dc.date.accessioned2012-11-26T08:49:28Z-
dc.date.available2012-11-26T08:49:28Z-
dc.date.issued2008en_US
dc.identifier.citationJournal Of Physics Condensed Matter, 2008, v. 20 n. 41en_US
dc.identifier.issn0953-8984en_US
dc.identifier.urihttp://hdl.handle.net/10722/175155-
dc.description.abstractUsing a simplified toy model, we study the quantum coherence effect in the spin-polarized transport of nano-magnets. A density matrix master equation is used to describe the correlation in the magnet. Through comparison with the classical rate equation, the coherence effect is clearly demonstrated. We find that the interaction between the spin-polarized current and the nano-magnet can be tuned by changing the bias voltage. At small bias voltage, the ferromagnetic lead will induce an antiferromagnetic exchange field. This exchange field is raised from the dynamics of the nondiagonal reduced density matrix elements of the nano-magnet. It is an obvious coherence effect and is beyond the scope of the classical rate equation. When bias voltage increases, tunneling becomes important and the dominating spin control mechanism is the spin accumulation which has been well studied in recent works (Timm and Elste 2006 Phys. Rev. B 73 235304, Timm 2007 Phys. Rev. B 76 014421, Misiorny and Barnas 2007 Phys. Rev. B 76 054448, Barnas et al 2000 Phys. Rev. B 62 12363). Our results obviously imply that the coherence effect in the spin-polarized transport of the nano-magnet cannot be ignored even in the collinear structure. This phenomenon is quite different from the case of the quantum dot (QD) spin valve which means that the classical rate equation, which is widely used in the study of the QD spin valve, is invalid for the nano-magnet-based spin valve. A density matrix description becomes essential. Our results are helpful for future investigations of nano-magnet devices. © 2008 IOP Publishing Ltd.en_US
dc.languageengen_US
dc.publisherInstitute of Physics Publishing. The Journal's web site is located at http://www.iop.org/Journals/jpcmen_US
dc.relation.ispartofJournal of Physics Condensed Matteren_US
dc.titleQuantum coherence effect in spin-polarized transport through nano-magnetsen_US
dc.typeArticleen_US
dc.identifier.emailGao, J: jhgao@hku.hken_US
dc.identifier.authorityGao, J=rp00698en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1088/0953-8984/20/41/415216en_US
dc.identifier.scopuseid_2-s2.0-56349128228en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-56349128228&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume20en_US
dc.identifier.issue41en_US
dc.identifier.isiWOS:000259693500023-
dc.publisher.placeUnited Kingdomen_US
dc.identifier.scopusauthoridGao, J=14021339900en_US
dc.identifier.scopusauthoridSun, Q=34572810700en_US
dc.identifier.scopusauthoridXie, XC=13502915800en_US

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