新型非局域磁纳米开关的原理和研究进展
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摘要
利用磁体进行信息记录的器件都需要操控磁体的磁矩,即使得磁体的磁矩翻转(磁化反转),从而实现"0"和"1"的信息转化。目前,实现纳米磁体磁矩翻转的方法主要有3种,即最传统的利用外磁场的方法、利用自旋转矩方法和利用自旋轨道矩的方法。后2种基于自旋矩的磁矩操控方法不需要外磁场,方便而且节能,不论是技术层面还是物理层面,都为科技人员展开了辽阔的研究空间。自旋轨道矩的发现始于近年自旋轨道耦合的研究,特别是自旋霍尔效应的研究。自旋霍尔效应和逆自旋霍尔效应现在被公认为是一种自旋操控的有效手段,它通过对铁磁/非磁双层系统上的铁磁体施加自旋矩使其磁矩翻转,并能探测由自旋注入或泵浦方法产生的自旋电流。本文综述了基于自旋霍尔效应等新物理效应的纳米磁体磁矩翻转的原理和研究进展情况。从应用和测量观点出发,磁矩翻转的非局域控制对于发展新型磁存储等自旋电子器件具有更大意义。本文介绍了几种主要的非局域自旋器件对材料的要求,对几种主要的材料参数进行了初步汇总。
For the information recording devices using magnets, it is required to manipulate the magnetic moments, in other words, to flip the magnetic moments of magnets(magnetization switching), so as to realize the information transformation between "0" and "1". Now there exist mainly three kinds of methods for realizing this goal. The first one are the most traditional one, which uses external magnetic field to reach magnetization switching. The second method was put forward in 1996, which switches the magnetization bythe so called spin transfer torque(STT). The third one was suggested recently, instead of STT, it uses the spin-orbit torque(SOT). The latter two methods are based on the spin torque, they are convenient and energy saving, especially, they do not need external magnetic field. They open the way for scientists and technology personnel for the study in both technical level and physical level. The discovery of spin- orbit torque comes from the research of spin-orbit coupling, especially the research of the spin hall effect in recent years. Spin hall effect and reverse spin hall effect are now widely recognized as a kind of effective means for the manipulating of spin configuration.By exerting spin torque on the magnet of the ferromagnetic/nonmagnetic bilayer system to flip the magnetic moment of the magnet, spin Hall effect can be used to detect the spin current generated by the spin injection or spin pump method. In this paper, the principle and research progress of the magnetization switching of nanomagnets related with the new physical effects such as spin hall effect are reviewed. From the application and measuring point of view, non-local manipulating for the magnetization switching is with greater significance for the development of new type of spintronic devices in the field of magnetic storage. Several kinds of main non-local based spin devices are introduced here, their requirements for materials are also discussed. At the end, part of the parameters of several main materials used in these non-local devices are summarized preliminary.
For the information recording devices using magnets, it is required to manipulate the magnetic moments, in other words, to flip the magnetic moments of magnets(magnetization switching), so as to realize the information transformation between "0" and "1". Now there exist mainly three kinds of methods for realizing this goal. The first one are the most traditional one, which uses external magnetic field to reach magnetization switching. The second method was put forward in 1996, which switches the magnetization bythe so called spin transfer torque(STT). The third one was suggested recently, instead of STT, it uses the spin-orbit torque(SOT). The latter two methods are based on the spin torque, they are convenient and energy saving, especially, they do not need external magnetic field. They open the way for scientists and technology personnel for the study in both technical level and physical level. The discovery of spin- orbit torque comes from the research of spin-orbit coupling, especially the research of the spin hall effect in recent years. Spin hall effect and reverse spin hall effect are now widely recognized as a kind of effective means for the manipulating of spin configuration.By exerting spin torque on the magnet of the ferromagnetic/nonmagnetic bilayer system to flip the magnetic moment of the magnet, spin Hall effect can be used to detect the spin current generated by the spin injection or spin pump method. In this paper, the principle and research progress of the magnetization switching of nanomagnets related with the new physical effects such as spin hall effect are reviewed. From the application and measuring point of view, non-local manipulating for the magnetization switching is with greater significance for the development of new type of spintronic devices in the field of magnetic storage. Several kinds of main non-local based spin devices are introduced here, their requirements for materials are also discussed. At the end, part of the parameters of several main materials used in these non-local devices are summarized preliminary.
引文
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[22]Pi K.,Han W,McC reary K M,et al.Manipulation of spin transport in graphene by surface chemical doping[J].Phys.Rev.Lett.,2010,104:187201.
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[25]Niimi Y,Suzuki H,Kawanishi Y,et al.Extrinsic spin Hall effects measured with lateral spin valve structures[J].Phys.Rev.B,2014,89:054401.
[26]Haney P M,Lee H W,Lee K J,et al.Current induced torques and interfacial spin-orbit coupling:Semiclassical modeling[J].Phys.Rev.B,2013,87:174411.
[27]Niimi Y,Kawanishi Y,Wei D H,et al.,Giant spin Hall effect induced by skew scattering from Bismuth impurities inside thin film CuB i alloys[J].Phys.Rev.Lett.,2012,109:156602.
[28]Balakrishnan,J.,Koon,G.K.W.,Jaiswal,M.,et al.Colossalenhancement of spin-orbit coupling in weakly hydrogenated graphene[J].Nat.Phys.,2013,9:284-287.
[29]Gambardella P and Miron I M.Current-induced spin-orbit torques[J].Phil.Trans.R.Soc.A,2011,369:3175-3197.
[30]Kim K W,Seo S M,Ryu J,et al.Magnetization dynamics induced by in-plane currents in ultrathin magnetic nanostructures with Rashba spin-orbit coupling[J].Phys.Rev.B,2012,85:180404(R).
[31]Cercellier H,Didiot C,Fagot-Revurat Y,et al.Interplay between structural,chemical,and spectroscopic properties of Ag/Au(111)epitaxial ultrathin films:A way to tune the Rashba coupling[J],Phys.Rev.B,2006,73:195413.
[32]Ast C R,Henk J,Ernst A,et al.Giant spin splitting through surface alloying[J].Phys.Rev.Lett.,2007,98:186807.
[33]Balakrishnan J,Koon G K W,Avsar A,et al.Giant spin Hall effect in graphene grown by chemical vapour deposition[J].Nature Communi.,2014,5,DOI:10.1038/ncomms5748.
[34]Gradhand M.,Fedorov D.V.,Zahn P.,et al.Spin Hall angle versus spin diffusion length:Tailored by impurities[J],Phys.Rev.B,2010,81:245109.
[35]Gradhand M.,Fedorov D.V.,Zahn P.,et al.Perfect alloys for spin hall current-induced magnetization switching[J].SPIN,2012,2(2):1250010.
[2]Xu H Z,Chen X,and Liu J M..Chaos suppression in a spin-torque nano-oscillator[J].J.Appl.Phys.,2008,104:093919.
[3]Martinez E,Emori S,Perez N,et al.Current-driven dynamics of Dzyaloshinskii domain walls in the presence of in-plane fields:Full micromagnetic and one-dimensional analysis[J].J.Appl.Phys.,2014,115:213909.
[4]Robert L Stamps,Stephan Breitkreutz,Johan?kerman,et al.The 2014 Magnetism Roadmap[J].J.Phys.D:Appl.Phys.,2014,47:333001.
[5]Chang C Z,Zhang J S,Feng X,et al.Experimental observation of the quantum anomalous Hall effect in a magnetic topological insulator[J].Science,2013:340(6129):167-170.
[6]Guo G Y,Murakami S,Chen T-W,et al.Intrinsic spin Hall effect in platinum:first-principles calculations[J].Phys.Rev.Lett.,2008,100:096401.
[7]Liu L,Pai C F,Li Y,et al.Spin-Torque switching with the giant spin Hall effect of tantalum[J].Science,2012,336:555.
[8]Pai C F,Liu L Q,Li Y,et al.,Spin transfer torque devices utilizing the giant spin Hall effect of tungsten[J].Appl.Phys.Lett.,2012,101:122404.
[9]Valenzuela S O,Tinkham M.Direct electronic measurement of the spin Hall effect[J].Nature,2006,442:176-179.
[10]Saitoh E,Ueda M,Miyajima H,Tatara G.Conversion of spin current into charge current at room temperature:Inverse spin-Hall effect[J].Appl.Phys.Lett.,2006,88(18):182509.
[11]Zhang S F,Levy P M,and Fert A.Mechanisms of spin-polarized current driven magnetization switching[J].Phys.Rev.Lett.,2002,88:26601.
[12]Tan S G,Jalil M B A,Fujita T,et al.Spin dynamics under local gauge fields in chiral spin–orbit coupling systems[J].Ann.Phys.,2011,326:207.
[13]Obata K,Tatara G.Current-induced domain wall motion in Rashba spin-orbit system[J].Phys.Rev.B,2008,77:214429.
[14]Manchon A and Zhang S,Theory of nonequilibrium intrinsic spin torque in a single nanomagnet[J].Phys.Rev.B,2008,78:212405.
[15]Liu L Q,Moriyama T,Ralph D C,et al.,Spin-torque ferromagnetic resonance induced by the spin Hall effect[J].Phys.Rev.Lett.,2011,106:036601.
[16]Khvalkovskiy A V,Cros V,Apalkov D,et al.Matching domain-wall configuration and spin-orbit torques for efficient domain-wall motion[J].Phys.Rev.B,2013,87:020402(R).
[17]Wang X H,Manchon A.Rashba spin torque in an ultrathin ferromagnetic metal layer[J].2011,ar Xiv:1111.5466v1.
[18]Guop Z-Z.Effects of the channel material parameters on the spin-torque critical current of lateral spin valves[J].Superlattice Microst.,2014,75:468-476.
[19]郭子政.基于朗道-利夫席茨-吉尔伯特方程的自旋阀动力学研究进展[J].信息记录材料,2014,15(3):56-64.
[20]Behin-Aein B,Datta D,Sayeef S,Datta S.Proposal for an all-spin logic device with built-in memory[J].Nat.Nanotech.,2010,5:266.
[21]Behin-Aein B,Sarkar A,Srinivasan S,et al.Switching energy-delay of all spin logic devices[J].Appl.Phys.Lett.,2011,98:123510.
[22]Pi K.,Han W,McC reary K M,et al.Manipulation of spin transport in graphene by surface chemical doping[J].Phys.Rev.Lett.,2010,104:187201.
[23]Sakamoto Y,Hirahara T,Miyazaki H,et al.Spectroscopic evidence of a topological quantum phase transition in ultrathin Bi2Se3 films[J].Phys.Rev.B,2010,81:165432.
[24]郭子政,邓海东,黄佳声,等.应力调制的自旋转矩临界电流[J].物理学报,2014,63(13):138501.
[25]Niimi Y,Suzuki H,Kawanishi Y,et al.Extrinsic spin Hall effects measured with lateral spin valve structures[J].Phys.Rev.B,2014,89:054401.
[26]Haney P M,Lee H W,Lee K J,et al.Current induced torques and interfacial spin-orbit coupling:Semiclassical modeling[J].Phys.Rev.B,2013,87:174411.
[27]Niimi Y,Kawanishi Y,Wei D H,et al.,Giant spin Hall effect induced by skew scattering from Bismuth impurities inside thin film CuB i alloys[J].Phys.Rev.Lett.,2012,109:156602.
[28]Balakrishnan,J.,Koon,G.K.W.,Jaiswal,M.,et al.Colossalenhancement of spin-orbit coupling in weakly hydrogenated graphene[J].Nat.Phys.,2013,9:284-287.
[29]Gambardella P and Miron I M.Current-induced spin-orbit torques[J].Phil.Trans.R.Soc.A,2011,369:3175-3197.
[30]Kim K W,Seo S M,Ryu J,et al.Magnetization dynamics induced by in-plane currents in ultrathin magnetic nanostructures with Rashba spin-orbit coupling[J].Phys.Rev.B,2012,85:180404(R).
[31]Cercellier H,Didiot C,Fagot-Revurat Y,et al.Interplay between structural,chemical,and spectroscopic properties of Ag/Au(111)epitaxial ultrathin films:A way to tune the Rashba coupling[J],Phys.Rev.B,2006,73:195413.
[32]Ast C R,Henk J,Ernst A,et al.Giant spin splitting through surface alloying[J].Phys.Rev.Lett.,2007,98:186807.
[33]Balakrishnan J,Koon G K W,Avsar A,et al.Giant spin Hall effect in graphene grown by chemical vapour deposition[J].Nature Communi.,2014,5,DOI:10.1038/ncomms5748.
[34]Gradhand M.,Fedorov D.V.,Zahn P.,et al.Spin Hall angle versus spin diffusion length:Tailored by impurities[J],Phys.Rev.B,2010,81:245109.
[35]Gradhand M.,Fedorov D.V.,Zahn P.,et al.Perfect alloys for spin hall current-induced magnetization switching[J].SPIN,2012,2(2):1250010.