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

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	Quantum coherence effect in spin-polarized transport through nano-magnets
	Gao, JH ; Sun, QF ; Xie, XC
刊名	JOURNAL OF PHYSICS-CONDENSED MATTER
	2008
卷号	20 期号:41
关键词	ZERO-BIAS ANOMALIES DOTS TRANSISTORS
ISSN号	0953-8984
通讯作者	Gao, JH (reprint author), Chinese Acad Sci, Inst Phys, Beijing 10080, Peoples R China.
中文摘要	Using 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.
收录类别	SCI
资助信息	Chinese Academy of Sciences; US-DOE [DE-FG02-04ER46124]; NSF [CCF-052473]; NSF-China [10525418, 10734110]
语种	英语
公开日期	2013-09-24
内容类型	期刊论文
源URL	[http://ir.iphy.ac.cn/handle/311004/51647]
专题	物理研究所_物理所公开发表论文_物理所公开发表论文_期刊论文
推荐引用方式 GB/T 7714	Gao, JH,Sun, QF,Xie, XC. Quantum coherence effect in spin-polarized transport through nano-magnets[J]. JOURNAL OF PHYSICS-CONDENSED MATTER,2008,20(41).
APA	Gao, JH,Sun, QF,&Xie, XC.(2008).Quantum coherence effect in spin-polarized transport through nano-magnets.JOURNAL OF PHYSICS-CONDENSED MATTER,20(41).
MLA	Gao, JH,et al."Quantum coherence effect in spin-polarized transport through nano-magnets".JOURNAL OF PHYSICS-CONDENSED MATTER 20.41(2008).