有机材料器件自旋注入和输运特性研究
|
摘要
自旋电子学是现代凝聚态物理学极具研究潜力的领域之一。与传统的电子学不同,自旋电子学将电子的自旋特性和电荷特性相结合,其核心内容是研究自旋极化电子的注入、输运、探测及自旋控制,其目的是将器件的电特性、光特性和磁特性等组合在一起,实现新型的自旋电子器件。自旋电子学是电子学的重大发展,近十几年来不仅导致了高密度存储器这类重大应用性器件的出现,而且还导致了一些基础性的物理革命,如自旋流、自旋压、自旋霍尔效应等新物理概念或现象的出现。自旋电子学器件包括铁磁金属或磁性半导体与绝缘体、超导体、导体、半导体等构型的复合,也包括近几年提出的有机功能固体或纳米小分子器件。目前,一些原型器件已被设计出来,如Datta和Das设计了第一个自旋晶体管等。器件的实际应用需要解决如何有效地将自旋极化电流注入半导体的问题,这要求理论与实验研究中准确描述自旋注入、演变以及界面效应等。目前研究发现,注入电流的自旋极化与两层材料的电阻之比密切相关,而电阻不匹配正是传统材料难以实现高自旋注入效率的原因所在。
相对于普通固体材料,柔软的有机半导体(OSCs:Organic semiconductors)可以和磁性层形成良好的接触,能有效减少自旋在界面的散射。由于有机材料弱的自旋-轨道耦合和超精细相互作用,载流子的自旋驰豫时间比较长,因而有机材料是实现自旋极化输运的理想候选材料。不同于传统的无机半导体中的载流子是电子,有机半导体中的载流子是极化子、双极化子和孤子等准例子,它们具有更复杂的电荷自旋关系,使有机自旋器件具有更丰富的特性。从小分子到高分子,人们对有机材料的电磁光等特性的认识越来越深入,无论从量子理论还是从经典理论出发,都得到了与实验具有可比性的理论结果。特别地,近几年来将有机半导体与自旋电子学结合,人们得到了一些令人振奋的新现象和新效应,行成了一个新的学科分支——有机自旋电子学。
有机自旋电子学是研究有机功能材料及其相关器件中的自旋产生、消灭、转移与存储等物理现象和物理机理的学科。它包含与化学交叉的有机材料和与物理学科交叉的自旋电子学两个领域。将二者结合,探讨有机材料在自旋电子学领域的应用显然具有重要的基础研究价值和潜在的应用背景,这也是当前国际上许多课题组密切关注的一个研究方向。
2002年Dediu课题组首次报道了有机材料中的自旋注入和输运,他们采用半金属CMR材料La_xSr_(1-x)MnO_3(LSMO)作极化电子给体,有机层采用sexithenyl(T_6),实验发现了负磁电阻,表明有机层内存在自旋极化注入,两电极之间的输运电流是自旋极化的。近几年,已经有很多实验验证了有机材料中的自旋注入和输运现象。如2004年,Xiong等人制备了LSMO/Alq_3/Co自旋阀,测得低温下可以实现40%的磁电阻效应:Majumdar等人采用LSMO作自旋极化电极,研究了LSMO/polymer/Co结构中的自旋极化注入现象,着重讨论了界面效应的影响等等。
对有机半导体中自旋注入和输运的理论研究包括以Xie等人为代表的量子理论和以Smith和Z.G.Yu等人为代表经典理论两个方面。前者能够描述自旋极化输运的微观机理,而后者可以得到一些可以与实验比较的物理量。近几年,人们已经对有机材料中的自旋极化注入和输运做了大量的理论工作。但是一些具体的问题人们还不是很清楚,例如,有机半导体中极化子和双极化子之间的转化对自旋极化注入和输运的影响;有机半导体中双极化子的浓度有什么因素决定?铁磁/有机半导体界面处磁性原子对有机半导体的渗透对于自旋极化注入和输运的影响等等。因此本论文将基于经典的漂移—扩散理论对上述问题展开相应研究,研究内容和结果如下:
1、极化子和双极化子对自旋极化注入和输运的影响
由于有机半导体具有强的电子—晶格相互作用,因此注入的电子将导致晶格发生畸变,最后形成一些电荷自陷态,如极化子和双极化子等。极化子具有1/2自旋,但双极化子不携带自旋。有机半导体中的极化子和双极化子并不是完全无关的,在外界条件,如温度、压力或者外场等作用下,两个自旋极化子可以湮灭成一个不带自旋的双极化子,一个双极化子也可以解离成两个极化子。Street等人曾经建立自旋不相关的极化子相互作用宏观模型,来分析极化子和双极化子之间的转化问题。人们在不考虑极化子和双极化子之间的转化的基础上,已经对它们在自旋输运中的作用有了初步的了解。但是正如上面所述,极化子和双极化子之间是存在转化的,这种转化对自旋极化注入和输运的影响会是怎样呢?本文在Street模型的基础上提出了一个自旋相关的极化子—极化子相互作用模型,来描述极化子和双极化子之间的转化,并用以研究有机半导体器件中自旋的注入和输运。基于包含了极化子与双极化子之间的转化效应和极化子自旋反转效应的漂移—扩散方程,我们计算了携带自旋的极化子和不携带自旋的双极化子的演化情况。研究发现极化子在有机半导体中的自旋极化输运中起主要作用。但是不同于传统的非有机半导体中的情况,不携带自旋的双极化子将影响有机器件中的自旋极化率。最后,讨论了载流子的自旋反转时间和迁移率对有机器件中自旋极化率的影响,我们发现大的自旋反转时间或迁移率有利于自旋在有机半导体中的输运。
2、有机自旋器件中影响双极化子浓度的因素
在第三章中,通过考虑极化子和双极化子之间的转化,我们发现双极化子将对自旋极化输运有重要的影响。另外,Bobbert等人认为产生有机磁电阻(OMAR:organic magnetoresistance)的原因是通过超精细相互作用,外磁场影响了自旋单态的生成几率,从而影响双极化子的含量。由此可见,双极化子作为载流子在有机自旋器件的自旋相关输运中起重要作用,它的浓度在一定程度上将决定有机自旋器件的性能。考虑极化子和双极化子之间的转化,我们基于漂移—扩散方程计算了双极化子的浓度分布情况,讨论了自旋反转时间、载流子迁移率等对双极化子浓度的影响。研究发现,极化子自旋反转时间的大小不影响双极化子的饱和浓度,但是自旋反转时间的劈裂不利于输运过程中双极化子的创生,这表明一个自旋非简并态不利于双极化子的创生。我们还发现,迁移率的大小对双极化子的饱和浓度没有影响。但是双极化子的饱和浓度随着双极化子和极化子迁移率之间的比值的减小而增大。
3、Co/有机半导体结构中Co渗透对自旋极化输运的影响
在有机器件如“Co/有机半导体/LSMO”的制备过程中,Co原子将渗透到柔软的有机层而形成磁性渗透层。我们考虑有机层中包含两个亚层:磁性渗透层和纯净有机层,并建立宏观动力学的自旋相关漂移—扩散方程研究了磁性渗透层对自旋极化率和器件磁电阻的影响。我们发现由于磁性渗透层不同于纯净有机层的自旋反转时间和迁移率,它将改变自旋的输运。由于渗透层中杂质原子或团簇的磁化作用,不同自旋的反转时间将不同,这种自旋反转时间的劈裂将有利于自旋极化率的输运。由于Co原子的额外散射,极化子在磁性渗透层中的迁移率将小于纯净有机层,这将减弱有机层中的自旋极化率,不利于自旋极化输运。对于一个给定的器件,我们讨论了磁性渗透层厚度对自旋极化率的影响。我们还用Julliere公式计算了“Co/有机半导体/LSMO”器件的磁电阻,得到了和实验数据符合的很好的结果。最后,我们讨论了界面磁性渗透对自旋注入的影响,发现在磁性渗透的影响下,界面是自旋选择性的,渗透层的磁化强度越大,自旋选择性越强,越有利于自旋的注入。
In the past few decades, spintronics as a very potential research area of condensed physics has attracted a lot of interests. Different from the classical electronics, spintronics involves both the electronic and spin characters of an electron. Fundamental studies of spintronics include investigations of spin injection, transport and detection in electronic materials, as well as spin manipulation. Its goal is to understand the interaction between the spin of electrons and crystalline environments and to make useful devices. Spintronics based on electronics, in the past decades, has resulted in not only a lot of applied device, such as high-density memory, but also some foundational renovation of physics, for example the emergence of some new physics concepts or phenomena such as spin current, spin valve, spin hall effect and so on. Spintronics device includes the conformations of magnetic metals or magnetic semiconductors with insulator, semiconductor, conductor, or superconductor, and the mixture of them, also includes molecule or nanometer device. Recently, several model devices have been schemed out. For example, Datta and Das designed the first spin transistor. However, the low efficiency of spin injection into semiconductor blocks the practical applications of such devices. The spin polarization of injected current is closely related to the ratio between resistances of the two layers. Therefore, more attentions should be paid to the influence of interfacial effects on the spin injection and spin evolution during the transport process.
Compared with conventional semiconductors, soft organic semiconductors (OSCs) have an opportunity to form a good interface with ferromagnetic metal (FM) or half-metal contacts, reducing the probability of spin scattering at the interface. The spin relaxation time is much longer than that of conventional semiconductors due to the weak spin-orbital and hyperfine interactions. Different from the traditional semiconductors, in which the carriers are electrons or holes, the carriers in OSCs are some "quasi-particles" such as polarons, bipolarons, and solitons. They have more complex spin-charge relation, which will result in more abundant properties of an organic spin device. The electric, magnetic and optical properties are unique in both the organic molecules and conjugated polymers. Up to now, the electric properties of quasi-one dimensional conducting polymers have been well understood. However, there is a lack of full understanding about the spin property of OSCs, since it is a new field called organic spintronics.
Organic spintronics is a subject that mainly study some physics mechanisms or phenomenon such as the creation, annihilate, transfer or storage of spin in the organic materials or device. It is an interdisciplinary subject, including two regions: organic materials in chemistry and spintronics in physics. Discussing the application of organic material in the spintronics apparently has significant value of basic research and potential foreground of applications. Therefore, it is an aspect that a lot of international research groups are interested in.
In 2002, Dediu's group firstly report the spin injection and transport in organic material, they use semi-metal material La_xSr_(1-x)MnO_3 (LSMO) as the source of electrons and sexithenyl (T_6) as the organic layer. It has been found that spin injected in the organic layer, and the current is spin polarized. In recent years, a lot of experiments have confirmed the spin injection and transport in organic materials, for example, in 2004, Xiong et al. have also observed spin injection and transport in a LSMO/Alq3/Co organic spin valve. The measured magnetoresistance can be as high as 40% at low temperature. Majumdar et al. have observed as much as 80% magnetoresistance (MR) at 5 K and 1.5% MR at room temperature in the structure of LSMO/polymer/Co organic spin valve. They also found that there is a thin spin-selective tunneling interface between LSMO and the polymer, which improves the spin injection.
Quantum theory used by Xie et al. and spin diffusion theory used by Smith, and Z. G. Yu et al. have been demonstrated successfully for studying the spin polarized injection and transport in OSCs. The quantum theory can describe the microcosmic mechanism of spin transport, while the macroscopical theory can obtain some results comparing to the experiments. In recent years, although much effort has been devoted to the study of organic spintronics, many questions are still under debate or indistinct. For example, effect of the transition between polarons and bipolarons on the spin injection and transport; the density of bipolarons depends on which factors; effect of the permeation of magnetic atoms at the FM/OSC interface on the spin injection and transport, and so on. In this paper, based on the classic drift-diffusion theory, we will investigate the above questions. The detailed research contents include:
1. Effect of polaron and bipolaron on the spin polarized injection and transport
Due to strong electron-lattice interaction in OSCs, injected electrons can induce the distortion of the lattice and result in charged self-trapped states called spin polarons or spinless bipolarons. A polaron has 1/2 spin, while a bipolaron has no spin. It should be pointed out that, due to the effect of temperature, pressure or external electric field, bipolarons and polarons in OSCs are not necessarily independent excitations. Two spin polarons may annihilate into one spinless bipolaron, while a bipolaron may also dissociate into two spin polarons. Street et al. has suggested a spin-irrelevant polarons interaction model to investigate the transition between polarons and bipolarons. Neglecting that transition, people have understood the preliminary effect of polarons and bipolarons. However, effect of the transition between polarons and bipolarons on the spin injection and transport is indistinct. Based on the Street's model, we suggested a spin related polaron-polaron model to describe the transition between polarons and bipolarons and investigated the spin injection and transport in an organic spin device. The evolutions of spin polarons and spinless bipolarons are calculated from the drift-diffusion equations, in which both the polaron-bipolaron transition and the spin flipping of a spin polaron are included. Then the spin polarized current is obtained. It is found that the polarons are responsible for the spin polarized transport in an OSC. Different from the case in a normal inorganic semiconductor, spinless bipolarons will affect the spin polarization of the OSC device. Finally, effects of the spin-flip time and the mobility of the carriers on the spin polarization in an organic device are discussed. It is found that large spin-flip time or mobility is helpful to the spin transport in OSCs.
2. The factors affecting the density of bipolaron in an OSC spin device
Through considering the transition between polarons and bipolarons, we found that bipolaron will apparent affect the spin polarized transport in the chapter III. Otherwise, Bobbert et al. considered that the influence of magnetic field on the density of bipolaron resulted in the organic magnetoresistance (OMAR). It can be seen that bipolaron as one of carriers play an important role in the spin transport, its density will decide the property of organic spin device to some extent. Considering the transition between polarons and bipolarons, we calculated the density distribution of carriers based on the drift-diffusion equations, and discussed the effect of the spin-flip time, mobility on the density of bipolarons. It was found that the value of the spin-flip time does not influence the saturation density of bipolarons, but the splitting of the spin-flip time is not helpful to the creation of bipolarons, which indicate a spin non-degenerate state in the OSC does not make for the creation of bipolarons. It also was found that the value of the mobility does not affect the saturation density of bipolarons. However, the saturation density of bipolarons will increase with the decrease of the proportion of mobility between polarons and bipolarons.
3. Effect of Co permeation on spin polarized transport in a Co/OSC structure
Co atoms will permeate into the soft organic material to form a magnetic permeated sublayer (MPS) during the fabrication of an organic spin device, such as Co/OSC/LSMO. We considered the OSC as a two-sublayer structure of MPS and pristine OSC, and then established a dynamic spin-diffusion equation to study the effect of MPS on the spin current polarization and the magnetoresistance of the device. It was found that the MPS will change the spin transport due to its different spin-flip time and mobility from that in the pristine OSC. The splitting of spin-flip times will be favorable to the spin polarization transport. Mobility of spin polarons in the MPS will be reduced due to the scattering of the Co atoms, which will weaken the spin polarization. For a given device, effect of the thickness of the MPS on the spin polarization is discussed. Also we calculated the magnetoresistance of a Co/OSC/LSMO device by the Julliere formula. A theoretical result which is consistent with the experimental data was obtained. Finally, effects of magnetic permeation at interface on spin injection are discussed. It can be found that the interface with magnetic permeation is spin selective, which will be helpful to spin injection. If the magnetization of permeation layer is large, the selectivity of interface will be strong.
相对于普通固体材料,柔软的有机半导体(OSCs:Organic semiconductors)可以和磁性层形成良好的接触,能有效减少自旋在界面的散射。由于有机材料弱的自旋-轨道耦合和超精细相互作用,载流子的自旋驰豫时间比较长,因而有机材料是实现自旋极化输运的理想候选材料。不同于传统的无机半导体中的载流子是电子,有机半导体中的载流子是极化子、双极化子和孤子等准例子,它们具有更复杂的电荷自旋关系,使有机自旋器件具有更丰富的特性。从小分子到高分子,人们对有机材料的电磁光等特性的认识越来越深入,无论从量子理论还是从经典理论出发,都得到了与实验具有可比性的理论结果。特别地,近几年来将有机半导体与自旋电子学结合,人们得到了一些令人振奋的新现象和新效应,行成了一个新的学科分支——有机自旋电子学。
有机自旋电子学是研究有机功能材料及其相关器件中的自旋产生、消灭、转移与存储等物理现象和物理机理的学科。它包含与化学交叉的有机材料和与物理学科交叉的自旋电子学两个领域。将二者结合,探讨有机材料在自旋电子学领域的应用显然具有重要的基础研究价值和潜在的应用背景,这也是当前国际上许多课题组密切关注的一个研究方向。
2002年Dediu课题组首次报道了有机材料中的自旋注入和输运,他们采用半金属CMR材料La_xSr_(1-x)MnO_3(LSMO)作极化电子给体,有机层采用sexithenyl(T_6),实验发现了负磁电阻,表明有机层内存在自旋极化注入,两电极之间的输运电流是自旋极化的。近几年,已经有很多实验验证了有机材料中的自旋注入和输运现象。如2004年,Xiong等人制备了LSMO/Alq_3/Co自旋阀,测得低温下可以实现40%的磁电阻效应:Majumdar等人采用LSMO作自旋极化电极,研究了LSMO/polymer/Co结构中的自旋极化注入现象,着重讨论了界面效应的影响等等。
对有机半导体中自旋注入和输运的理论研究包括以Xie等人为代表的量子理论和以Smith和Z.G.Yu等人为代表经典理论两个方面。前者能够描述自旋极化输运的微观机理,而后者可以得到一些可以与实验比较的物理量。近几年,人们已经对有机材料中的自旋极化注入和输运做了大量的理论工作。但是一些具体的问题人们还不是很清楚,例如,有机半导体中极化子和双极化子之间的转化对自旋极化注入和输运的影响;有机半导体中双极化子的浓度有什么因素决定?铁磁/有机半导体界面处磁性原子对有机半导体的渗透对于自旋极化注入和输运的影响等等。因此本论文将基于经典的漂移—扩散理论对上述问题展开相应研究,研究内容和结果如下:
1、极化子和双极化子对自旋极化注入和输运的影响
由于有机半导体具有强的电子—晶格相互作用,因此注入的电子将导致晶格发生畸变,最后形成一些电荷自陷态,如极化子和双极化子等。极化子具有1/2自旋,但双极化子不携带自旋。有机半导体中的极化子和双极化子并不是完全无关的,在外界条件,如温度、压力或者外场等作用下,两个自旋极化子可以湮灭成一个不带自旋的双极化子,一个双极化子也可以解离成两个极化子。Street等人曾经建立自旋不相关的极化子相互作用宏观模型,来分析极化子和双极化子之间的转化问题。人们在不考虑极化子和双极化子之间的转化的基础上,已经对它们在自旋输运中的作用有了初步的了解。但是正如上面所述,极化子和双极化子之间是存在转化的,这种转化对自旋极化注入和输运的影响会是怎样呢?本文在Street模型的基础上提出了一个自旋相关的极化子—极化子相互作用模型,来描述极化子和双极化子之间的转化,并用以研究有机半导体器件中自旋的注入和输运。基于包含了极化子与双极化子之间的转化效应和极化子自旋反转效应的漂移—扩散方程,我们计算了携带自旋的极化子和不携带自旋的双极化子的演化情况。研究发现极化子在有机半导体中的自旋极化输运中起主要作用。但是不同于传统的非有机半导体中的情况,不携带自旋的双极化子将影响有机器件中的自旋极化率。最后,讨论了载流子的自旋反转时间和迁移率对有机器件中自旋极化率的影响,我们发现大的自旋反转时间或迁移率有利于自旋在有机半导体中的输运。
2、有机自旋器件中影响双极化子浓度的因素
在第三章中,通过考虑极化子和双极化子之间的转化,我们发现双极化子将对自旋极化输运有重要的影响。另外,Bobbert等人认为产生有机磁电阻(OMAR:organic magnetoresistance)的原因是通过超精细相互作用,外磁场影响了自旋单态的生成几率,从而影响双极化子的含量。由此可见,双极化子作为载流子在有机自旋器件的自旋相关输运中起重要作用,它的浓度在一定程度上将决定有机自旋器件的性能。考虑极化子和双极化子之间的转化,我们基于漂移—扩散方程计算了双极化子的浓度分布情况,讨论了自旋反转时间、载流子迁移率等对双极化子浓度的影响。研究发现,极化子自旋反转时间的大小不影响双极化子的饱和浓度,但是自旋反转时间的劈裂不利于输运过程中双极化子的创生,这表明一个自旋非简并态不利于双极化子的创生。我们还发现,迁移率的大小对双极化子的饱和浓度没有影响。但是双极化子的饱和浓度随着双极化子和极化子迁移率之间的比值的减小而增大。
3、Co/有机半导体结构中Co渗透对自旋极化输运的影响
在有机器件如“Co/有机半导体/LSMO”的制备过程中,Co原子将渗透到柔软的有机层而形成磁性渗透层。我们考虑有机层中包含两个亚层:磁性渗透层和纯净有机层,并建立宏观动力学的自旋相关漂移—扩散方程研究了磁性渗透层对自旋极化率和器件磁电阻的影响。我们发现由于磁性渗透层不同于纯净有机层的自旋反转时间和迁移率,它将改变自旋的输运。由于渗透层中杂质原子或团簇的磁化作用,不同自旋的反转时间将不同,这种自旋反转时间的劈裂将有利于自旋极化率的输运。由于Co原子的额外散射,极化子在磁性渗透层中的迁移率将小于纯净有机层,这将减弱有机层中的自旋极化率,不利于自旋极化输运。对于一个给定的器件,我们讨论了磁性渗透层厚度对自旋极化率的影响。我们还用Julliere公式计算了“Co/有机半导体/LSMO”器件的磁电阻,得到了和实验数据符合的很好的结果。最后,我们讨论了界面磁性渗透对自旋注入的影响,发现在磁性渗透的影响下,界面是自旋选择性的,渗透层的磁化强度越大,自旋选择性越强,越有利于自旋的注入。
In the past few decades, spintronics as a very potential research area of condensed physics has attracted a lot of interests. Different from the classical electronics, spintronics involves both the electronic and spin characters of an electron. Fundamental studies of spintronics include investigations of spin injection, transport and detection in electronic materials, as well as spin manipulation. Its goal is to understand the interaction between the spin of electrons and crystalline environments and to make useful devices. Spintronics based on electronics, in the past decades, has resulted in not only a lot of applied device, such as high-density memory, but also some foundational renovation of physics, for example the emergence of some new physics concepts or phenomena such as spin current, spin valve, spin hall effect and so on. Spintronics device includes the conformations of magnetic metals or magnetic semiconductors with insulator, semiconductor, conductor, or superconductor, and the mixture of them, also includes molecule or nanometer device. Recently, several model devices have been schemed out. For example, Datta and Das designed the first spin transistor. However, the low efficiency of spin injection into semiconductor blocks the practical applications of such devices. The spin polarization of injected current is closely related to the ratio between resistances of the two layers. Therefore, more attentions should be paid to the influence of interfacial effects on the spin injection and spin evolution during the transport process.
Compared with conventional semiconductors, soft organic semiconductors (OSCs) have an opportunity to form a good interface with ferromagnetic metal (FM) or half-metal contacts, reducing the probability of spin scattering at the interface. The spin relaxation time is much longer than that of conventional semiconductors due to the weak spin-orbital and hyperfine interactions. Different from the traditional semiconductors, in which the carriers are electrons or holes, the carriers in OSCs are some "quasi-particles" such as polarons, bipolarons, and solitons. They have more complex spin-charge relation, which will result in more abundant properties of an organic spin device. The electric, magnetic and optical properties are unique in both the organic molecules and conjugated polymers. Up to now, the electric properties of quasi-one dimensional conducting polymers have been well understood. However, there is a lack of full understanding about the spin property of OSCs, since it is a new field called organic spintronics.
Organic spintronics is a subject that mainly study some physics mechanisms or phenomenon such as the creation, annihilate, transfer or storage of spin in the organic materials or device. It is an interdisciplinary subject, including two regions: organic materials in chemistry and spintronics in physics. Discussing the application of organic material in the spintronics apparently has significant value of basic research and potential foreground of applications. Therefore, it is an aspect that a lot of international research groups are interested in.
In 2002, Dediu's group firstly report the spin injection and transport in organic material, they use semi-metal material La_xSr_(1-x)MnO_3 (LSMO) as the source of electrons and sexithenyl (T_6) as the organic layer. It has been found that spin injected in the organic layer, and the current is spin polarized. In recent years, a lot of experiments have confirmed the spin injection and transport in organic materials, for example, in 2004, Xiong et al. have also observed spin injection and transport in a LSMO/Alq3/Co organic spin valve. The measured magnetoresistance can be as high as 40% at low temperature. Majumdar et al. have observed as much as 80% magnetoresistance (MR) at 5 K and 1.5% MR at room temperature in the structure of LSMO/polymer/Co organic spin valve. They also found that there is a thin spin-selective tunneling interface between LSMO and the polymer, which improves the spin injection.
Quantum theory used by Xie et al. and spin diffusion theory used by Smith, and Z. G. Yu et al. have been demonstrated successfully for studying the spin polarized injection and transport in OSCs. The quantum theory can describe the microcosmic mechanism of spin transport, while the macroscopical theory can obtain some results comparing to the experiments. In recent years, although much effort has been devoted to the study of organic spintronics, many questions are still under debate or indistinct. For example, effect of the transition between polarons and bipolarons on the spin injection and transport; the density of bipolarons depends on which factors; effect of the permeation of magnetic atoms at the FM/OSC interface on the spin injection and transport, and so on. In this paper, based on the classic drift-diffusion theory, we will investigate the above questions. The detailed research contents include:
1. Effect of polaron and bipolaron on the spin polarized injection and transport
Due to strong electron-lattice interaction in OSCs, injected electrons can induce the distortion of the lattice and result in charged self-trapped states called spin polarons or spinless bipolarons. A polaron has 1/2 spin, while a bipolaron has no spin. It should be pointed out that, due to the effect of temperature, pressure or external electric field, bipolarons and polarons in OSCs are not necessarily independent excitations. Two spin polarons may annihilate into one spinless bipolaron, while a bipolaron may also dissociate into two spin polarons. Street et al. has suggested a spin-irrelevant polarons interaction model to investigate the transition between polarons and bipolarons. Neglecting that transition, people have understood the preliminary effect of polarons and bipolarons. However, effect of the transition between polarons and bipolarons on the spin injection and transport is indistinct. Based on the Street's model, we suggested a spin related polaron-polaron model to describe the transition between polarons and bipolarons and investigated the spin injection and transport in an organic spin device. The evolutions of spin polarons and spinless bipolarons are calculated from the drift-diffusion equations, in which both the polaron-bipolaron transition and the spin flipping of a spin polaron are included. Then the spin polarized current is obtained. It is found that the polarons are responsible for the spin polarized transport in an OSC. Different from the case in a normal inorganic semiconductor, spinless bipolarons will affect the spin polarization of the OSC device. Finally, effects of the spin-flip time and the mobility of the carriers on the spin polarization in an organic device are discussed. It is found that large spin-flip time or mobility is helpful to the spin transport in OSCs.
2. The factors affecting the density of bipolaron in an OSC spin device
Through considering the transition between polarons and bipolarons, we found that bipolaron will apparent affect the spin polarized transport in the chapter III. Otherwise, Bobbert et al. considered that the influence of magnetic field on the density of bipolaron resulted in the organic magnetoresistance (OMAR). It can be seen that bipolaron as one of carriers play an important role in the spin transport, its density will decide the property of organic spin device to some extent. Considering the transition between polarons and bipolarons, we calculated the density distribution of carriers based on the drift-diffusion equations, and discussed the effect of the spin-flip time, mobility on the density of bipolarons. It was found that the value of the spin-flip time does not influence the saturation density of bipolarons, but the splitting of the spin-flip time is not helpful to the creation of bipolarons, which indicate a spin non-degenerate state in the OSC does not make for the creation of bipolarons. It also was found that the value of the mobility does not affect the saturation density of bipolarons. However, the saturation density of bipolarons will increase with the decrease of the proportion of mobility between polarons and bipolarons.
3. Effect of Co permeation on spin polarized transport in a Co/OSC structure
Co atoms will permeate into the soft organic material to form a magnetic permeated sublayer (MPS) during the fabrication of an organic spin device, such as Co/OSC/LSMO. We considered the OSC as a two-sublayer structure of MPS and pristine OSC, and then established a dynamic spin-diffusion equation to study the effect of MPS on the spin current polarization and the magnetoresistance of the device. It was found that the MPS will change the spin transport due to its different spin-flip time and mobility from that in the pristine OSC. The splitting of spin-flip times will be favorable to the spin polarization transport. Mobility of spin polarons in the MPS will be reduced due to the scattering of the Co atoms, which will weaken the spin polarization. For a given device, effect of the thickness of the MPS on the spin polarization is discussed. Also we calculated the magnetoresistance of a Co/OSC/LSMO device by the Julliere formula. A theoretical result which is consistent with the experimental data was obtained. Finally, effects of magnetic permeation at interface on spin injection are discussed. It can be found that the interface with magnetic permeation is spin selective, which will be helpful to spin injection. If the magnetization of permeation layer is large, the selectivity of interface will be strong.
引文
[1] BaibichM N . Phys. Rev. Lett., 61,2472 (1988)
[2] Baibich M N, et al. Phys. Rev. Lett., 61: 2472 (1988)
[3] Bamas J, et al. Phys. Rev. B, 42: 8110 (1990)
[4] Wolf S A, et al. Science, 294: 1488 (2001)
[5] Igor zutic, Jaroslav Fabian, S. Das Sarma, Rev. Mod. Phys., 76: 323 (2004)
[6] Meservey R, Phys. Rev. Lett., 25: 1270 (1970)
[7] Johnson M, Silsbee R H, Phys. Rev. Lett, 55:1790 (1985)
[8] Monzon F G, Tang H X, Roukes M L, Phys. Rev. Lett, 84: 5022 (2000)
[9] Ohno Y, et al. Nature, 402: 790 (1999)
[10] Datta S, Das B, Appl. Phys. Lett, 56 (7): 665 (1990)
[11] Chen C D, et al. Phys. Rev. Lett, 88: 047004 (2002)
[12] Julliere M, Phys. Lett. 54,225-226 (1975)
[13] Johnson M, and R. H. Silsbee, Phys. Rev. Lett. 55,1790-1793 (1985)
[14] Johnson M, and R. H. Silsbee, Phys. Rev. Lett. 60, 377 (1988)
[15] Mott N. F, Proc. R. Soc. London, Ser. A153, 699-717 (1936)
[16] Fert A, and I. A. Campbell, Phys. Rev. Lett. 21,1190-1192 (1968)
[17] Z. G. Yu and M. E. Flatte Phys. Rev. B. 66,235302 (2002).
[18] E. I. Rashba, Phys. Rev. B. 62, R16267 (2000).
[19] D. L. Smith and R. N. Silver, Phys. Rev. B. 64, 045323 (2001).
[20] A. Fert and H. Jaffres, Phys. Rev. B. 64,184420 (2002).
[21] S. Agrawal, M. B. A. Jalil, K. L. Teo, and Y. F. Liew, J. Appl. Phys. 97,103907 (2005)
[22] J. D. Albrecht and D. L. Smith, Phys. Rev. B. 66,113303, (2002).
[23] Karsten Flensberg, Thomas Stibius Jensen, and Niels Asger Mortensen, Phys. Rev. B. 64, 245308, (2001).
[24] J-Ph Ansermet, J. Phys.: Condens. Matter 10, 6027-6050 (1998)
[25] D'yakonov, M. I, and V. I. Perel', 1971e, Fiz. Tverd. Tela 13, 3581-3585 [Sov. Phys. Solid State 13, 3023-3026 (1971)]
[26] D'yakonov, M. I., and V. I. Perel', 1973b, "Optical orientation in a system of electrons and lattice nuclei in semiconductors Theory," Zh. Eksp. Teor. Fiz. 38, 362-376 [Sov. Phys. JETP 38,177-183 (1973)].
[27] Elliott, R. J., Phys. Rev. 96,266-279 (1954)
[28] Yafet, Y., J. Phys. Chem. Solids 21,99-104 (1961)
[29] Bir, G. L., A. G. Aronov, and G. E. Pikus, 1975, "Spin relaxation of electrons due to scattering by holes," Zh. Eksp. Teor. Fiz. 69, 1382-1397 [Sov. Phys. JETP 42, 705-712 (1976)].
[30] Ito T , Sh irakaw a H, Ikeda S. Simultaneous polymerization and format ion of polyacetylene film on the surface of concent rated so luble Ziegler2Type catalyst solution. J Polym Sci Polym Chem, 1974; 12: 11
[31] C. K. Chang, C. R. Fincher, Y. W. Park, et al, Phys. Rev. Lett 39 1098 (1977)
[32] W. P. Su, J. R. Schrieffer, and A. J. Heeger, Phys. Rev. Lett. 42,1698 (1979) Su W P, Sch rieffer J , Heeger A J. Solitons in polyacetylene. Phys Rev Lett, 1979; 42: 1698
[33] C. K. Chang, E. J. Louis, M. A. Druy et al, J Am Chem Soc 100 1013 (1978)
[34] R. L. Greene et al, Phys. Rev. Lett 34 577 (1975)
[35] Y. Park et al, J. Chem. Phys 73 946 (1980)
[36] H. Naarmann, N. Theophilou, Synth Met 22 1 (1987)
[37] W. J. Feast, J. Tsibouklis, K. L. Pouwer, L. Gronendaal, and E. W. Meijer, Polymer 37 5017(1996)
[38] Schon J H, Berg S, Kloc Ch, et al. Ambipolar pentacene field effect transistors and inverters. Science, 287,1022 (2000)
[39] Jurchescu O D, Baas J and Palstra T T M, Appl. Phys. Lett. 84 3061 (2004)
[40] Rajca A, et al. Science, 2001,294: 1503
[41] Miller J S, et al. Chem Rev, 1988, 88: 201
[42] T. L. Makarova, B. Sundqvist, et al. Nature 413, 716 (2001)
[43] Y. V. Korshak, T. V. Medvedeva, A. A. Ovchinnikov, and V. N. Spector, Nature 326,370(1987)
[44] M. Takahashi, P. Turk, Y. Nakazawa, M. Tamura, K. Nozawa, D. Shioni, M. Ishikawa and M. Kinoshita, Phys. Rev. Lett. 67, 746 (1991)
[45] A. A. Ovchinnikov and V. N. Spector, Synth Met. 27, 615 (1988)
[46] Z. Fang, Z. L. Liu, and K. L. Yao, Phys. Rev. B 49, 3916 (1994)
[47] Z. Y. Sun, K. L. Yao, W. Yao, D. H. Zhang, and Z. L. Liu, Phys. Rev. B 77, 014416(2008).
[48] Tang CW , VanSlyke S A. Organic electroluminescent diodes. ApplPhys Lett, 1987; 51: 913
[49] Burroughes J H, Bradley D D C, Brown A R, et al. Light-emitting diodes based on conjugated polymers. Nature, 1990; 347: 539
[50] J. H. Burroughes, D. D C Bradley, A R Brown et al, Nature 347 539(1990)
[51] Z. Yang, I Sokolik, F. E Karasz, Macromolecules 26 1188(1993)
[52] E. G. J Staring, R C J E Demandt, D Braun et al, Adv Mater 6 488(1994)
[53] N. C. Greenham, S C Mora tti, D D C, et al, Nature 365 628(1993)
[54] Voss D, Nature, 2000, 442: 407
[55] R. H. Friend, R. W Gymer, A. B.Holmes, J. H. Burroughes, R. N. Marks, C. Taliani, D. D. C. Bradley, D. A. Santos, J. L.Bre'das, M. Logdlund, W. R. Salaneck, Nature 397 121(1999)
[56] D. Braun, A. J. Heeger, Appl. Phys. Lett 58 1982(1991)
[57] Z. L. Shen, P. E.Burrows, V. Bulovic, S. R. Forrest, M. E. Thompson, Science 276 2009; 78 729(1997)
[58] H. Sirringhaus, N. Tessler, R. H. Friend, Science 280,1741(1998)
[59] P. K. H. Ho, D. S. Thomas, R. H. Friend, N. Tessler, Science 285 233(1999)
[60] A. odabalapur, Z. ao, A. akhija, J. G. aquindanum, V. R. Raju, Y. Feng, H. E. Katz, J. Rogers, Appl. Phys. Lett 73 142; 32 267(1998)
[61] C. K. Chang, C. R. Fincher, Y. W. Park, A. J. Heeger, H. Shirakawa, E. J. Louis, S. C. Gau, and A. G. MacDiarmid, Phys. Rev. Lett. 39,1098-1101 (1977)
[62] C. K. Chiang, M. A. Druy, S. C. Gau, A. J. Heeger, E. J. Louis, A. G. MacDiarmid, Y. W. Park, and H. Shirakawa, J. Am. Chem. Soc. 100,1013 (1978)
[63] W. P. Su, J. R. Schrieffer, and A. J. Heeger, Phys. Rev. 22,2099 (1980)
[64] P. E. Peierls, Quantum Theory of Solids, Oxford University Press, London, 1955, 108
[65] 孙鑫 物理学进展 6, 1 (1986).
[66] V. Dediu, M. Murgia, F. C. Matacotta, C. Taliani, and S. Barbanera, Solid State Comm. 122,181 (2002).
[67] Xiong Z H, et al. Nature, 2004,427: 821
[68] T. S. Santos, J. S. Lee, P. Migdal, I. C. Lekshmi, B. Satpati, and J. S. Moodera, Phys. Rev. Lett. 98, 016601 (2007)
[69] M. Ouyang and D. D. Awschalom, Science 301, 1074 (2003)
[70] J. R. Petta, S. K. Slater, and D. C. Ralph, Phys. Rev. Lett. 93,136601 (2004)
[71] A. N. Pasupathy, R. C. Bialczak, J. Martinek, J. E. Grose, L. A. K. Donev, P. L. McEuen and D. C. Ralph, Science 306,86 (2004).
[72] T. L. Francis, O. Mermer, G. Veeraraghavan and M. Wohlgenannt, New Journal of Physics 6,185(2004)
[73] T. D. Nguyen, Y. Sheng, J. Rybicki, and M. Wohlgenannt, Phys. Rev. B, 77, 235209 (2008)
[74] O. Mermer, G. Veeraraghavan, T. L. Francis and M. Wohlgenannt, Solid State Commun. 134,631(2005).
[75] P. A. Bobbert, T. D. Nguyen, F. W. A.van Oost, B. Koopmans and M. Wohlgenannt, Phys.Rev.Lett. 99,216801 (2007).
[76] Li S, Chen L S, George T H, Sun X, Phys. Rev. B, 2004, 70: 075201.
[77] Zwolak M, Di Ventra M, Appl. Phys. Lett., 2002, 81: 925.
[78] S. J. Xie, K. H. Ahn, D. L. Smith, Phys. Rev. B, 2003, 67: 125202.
[79] J. Y. Fu, J. F. Ren, et al. Thin Solid Films 477 (2005) 212.
[80] J. Y. Fu, J. F. Ren, et al. Synthetic Metal 156 (2006) 370
[81] J. Y. Fu, J. F. Ren, X. J. Liu, D. S. Lie and S. J. Xie, Phys. Rev. B 73, 195401 (2006).
[82] J. Lei, H. Li, S. Yin and S. J. Xie, J. Phys. C 20, 095201 (2008).
[83] C. Toher and S. Sanvito, Phys. Rev. Lett. 99, 056801 (2007).
[84] E. G. Emberlya, G. Kirczenow, Chem. Phys. 281, 311 (2002).
[83]R.Pati,L.Senapati,P.M.Ajayan,and S.K.Nayak,Phys.Rev.B 68,100407(2006).
[86]D.Waldron,P.Haney,B.Larade,A.MacDonald,and H.Guo,Phys.Rev.Lett.96,166804(2006).
[87]J.H.Wei,S.J.Xie,L.M.Mei,J.Berakdar,and Y.J.Yan,New J.Phys.8,82(2006).
[88]J.H.Wei,S.J.Xie,L.M.Mei,J.Berakdar,and Y.J.Yan,Org.Electron.8,487(2007).
[89]R.Liu,S.Ke,H.U.Baranger and W.Yang,Nano Letters 5,1959(2005).
[90]H.Dalgleish and G.Kirczenow,Phys.Rev.B 73,235436(2006).
[91]P.P.Ruden and D.L.Smith,J.Appl.Phys.95,4898(2004).
[92]Z.G.Yu,M.A.Berding,and S.Krishnamurthy,Phys.Rev.B.71,060408(2005).
[93]Z.G.Yu,M.A.Berding,and S.Krishnamurthy,J.Appl.Phys.,97,024510(2005).
[94]J.F.Ren,et al.J.Appl.Phys.,2005,98:074503.
[95]J.F.Ren,J.Y.Fu,et al.J.Phys.:Condens.Matter 17(2005) 2341.
[96]Yubin Zhang,Junfeng Ren,Guichao Hu and Shijie Xie,Organic Electronics 9(2008) 687.
[97]Yubin Zhang,Junfeng Ren,Jie Lei,Shijie Xie,Organic Electronics,doi:10.1016/j.orgel.2009.02.005.
[98]R.A.Street,A.Salleo,and M.L.Chabinyc,Phys.Rev.B.68,085316(2003).
[99]P.A.Bobbert,T.D.Nguyen et al.Phys.Rev.Lett.99,216801(2007).
[100]任俊峰,付吉永,解士杰,物理(约稿),第35卷第10期,852-859(2006)
[101]任俊峰,付吉永,刘德胜,解士杰,物理学报,第53卷第11期,3814-3817(2004)
[102]J.F.Ren,J.Y.Fu,D.S.Liu,L.M.Mei,S.J.Xie,Synthic Metal 155,611-614(2005)
[103]任俊峰,张玉滨,解士杰,物理学报,第56卷第8期,4785-4790(2007)
[104]Junfeng Ren,Yubin Zhang,Shijie Xie,Organic Electronics 9,1017-1021(2008)
[105] Y. N. Ma, J. F. Ren, Y. B. Zhang, D. S. Liu, S. J. Xie, Chin. Phys. Lett. 24, 1697-1700(2007)
[106] Guichao Hu, Ying Guo, Jianhua Wei, and Shijie Xie, Phys. Rev. B 75, 165321 (2007)
[107] Guichao Hu, Keliang He, Shijie Xie, and Avadh Saxena, J. Chem. Phys. 129, 234708 (2008)
[1]半导体物理学,上册,叶良修 高等教育出版社,1983
[2]半导体物理学,刘恩科 朱秉生 罗晋生 西安交通大学出版社,1998
[3]Z.G.Yu and M.E.Flatte,Phys.Rev.B 66,235302(2002)
[4]Y.V.Pershin and V.Privman,Phys.Rev.Lett.90,256602(2003)
[5]Z.G.Yu and M.E.Flatte,Phys.Rev.B 66,201202(R)(2002)
[6]E.I.Rashba,Phys.Rev.B.62,R16267(2000).
[7]I.Zutic,J.Fabian,and S.Das Sarmal,Phys.Rev.Lett.88,066603(2002)
[8]Ivar Martin,Phys.Rev.B 67,014421(2003)
[1]See,e.g.,I.H.Campbell and D.L.Smith,Solid State Phys.55,1(2001).
[2]R.H.Friend,R.W.Gymer,A.B.Holmes,et al.,Nature 397,121(1999).
[3]S.Forrest,P.Burrows,and M.Thompson,IEEE Spectr.37,29(2000).
[4]D.Voss,Nature 407,442(2000).
[5]S.A.Wolf,D.D.Awschalom,R.A.Buhrman J.M.Daughton,S.von Molnar,M.L.Roukes,A.Y.Chtchelkanova,and D.M.Treger,Science 294,1488(2001).
[6]V.Dediu,M.Murgia,F.C.Matacotta,C.Taliani,and S.Barbanera,Solid State Comm.122,181(2002).
[7]Z.H.Xiong,Di Wu,Z.Valy Vardeny,and Jing Shi,Nature 427,821(2004).
[8]Sayani Majumdar,R.Laiho,P.Laukkanen,I.J.V(a)yrynen,Himadi S.Majumdar and R.(O|¨)sterbacka,Appl.Phys.Lett.89,122114(2006).
[9]Z.G.Yu,M.A.Berding,and S.Krishnamurthy,Phys.Rev.B.71,060408R (2005).
[10]S.J.Xie,K.H.Ahn,D.L.Smith,A.R.Bishop,andA.Saxena,Phys.Rev.B.67,125202(2003).
[11]D.L.Smith and R.N.Silver,Phys.Rev.B.64,045323(2001)
[12]P.P.Ruden and D.L.Smith,J.Appl.Phys.95,4898(2004).
[13]Z.G.Yu,M.A.Berding,and S.Krishnamurthy,J.Appl.Phys.97,024510(2005).
[14]J.F.Ren,J.Y.Fu,D.S.Liu,L.M.Mei,and S.J.Xie,J.Appl.Phys.98,074503(2005).
[15]J.F.Ren,J.Y.Fu,D.S.Liu,L.M.Mei,and S.J.Xie,J.Phys.:Condens.Matter 17,2341 (2005).
[16] A. Saxena, T. Castan, A. Planes, M. Porta, Y. Kishi, T. A. Lograsso, D. Viehland, M. Wuttig, and M. De Graef, Phys. Rev. Lett. 90,197203 (2004).
[17] M. J. Nowak, D. Spiegel, S. Hotta. A. J. Heeger, and P. A. Pincus, Macromolecules 22,2917 (1989).
[18] Matheus Paes Lima and Geraldo Magela e Silva, Phys. Rev. B. 74,224304 (2006)
[19] Shi-jie Xie, Liang-mo Mei, and D. L. Lin, Phys. Rev. B. 50,13364 (1994)
[20] Yuriy V. Pershin and Vlandimir Privman, Phys. Rev. Lett. 90,256602 (2003).
[21] R. A. Street, A. Salleo, and M. L. Chabinyc, Phys. Rev. B. 68, 085316 (2003).
[22] A. Salleo and R. A. Street, Phys. Rev. B. 70, 235324 (2004).
[23] Z. G. Yu and M. E. Flatte, Phys. Rev. B. 66, 235302 (2002).
[24] T. C. Chung, J. H. Kaufman, A. J. Heeger, and F. Wudl, Phys. Rev. B. 30, 702 (1984).
[25] K. E. Ziemelis, A. T. Hussain, D. D. C. Bradley, R. H. Friend, J. Ruhe, and G. Wegner, Phys. Rev. Lett. 66,2231 (1991)
[1] P. P. Ruden and D. L. Smith, J. Appl. Phys. 95,4898 (2004).
[2] Z. G. Yu, M. A. Berding, and S. Krishnamurthy, J. Appl. Phys. 97, 024510 (2005).
[3] Z. G. Yu, M. A. Berding, and S. Krishnamurthy, Phys. Rev. B. 71, 060408 (2005).
[4] S. J. Xie, K. H. Ahn, D. L. Smith, A. R. Bishop, and A. Saxena, Phys. Rev. B. 67, 125202 (2003).
[5] A. J. Heeger, S. Kivelson, J. R. Schrieffer, and W. P. Su, Rev. Mod. Phys. 60, 781 (1988).
[6] P. S. Davids, A. Saxena, and D. L. Smith, J. Appl. Phys. 78,4244 (1995).
[7] Geraldo Magela e Silva, Phys. Rev. B. 61,10777 (2000).
[8] J. C. Scott, P. Pfluger, M. T. Krounbi, and G. B. Street, Phys. Rev. B. 28,2140 (1983).
[9] F. Genoud, M. Guglielmi, M. Nechtschein, E. Genies, and M. Salmon, Phys. Rev. Lett. 55,118(1985)
[10] J. F. Ren, J. Y. Fu, D. S. Liu, L. M. Mei, and S. J. Xie, J. Appl. Phys. 98, 074503 (2005).
[11] D. L. Smith and R. N. Silver, Phys. Rev. B. 64, 045323 (2001)
[12] J. F. Ren, J. Y. Fu, D. S. Liu, L. M. Mei, and S. J. Xie, J. Appl. Phys. 98, 074503 (2005).
[13] J. F. Ren, J. Y. Fu, D. S. Liu, L. M. Mei, and S. J. Xie, J. Phys.: Condens. Matter 17,2341 (2005).
[14] Yubin Zhang, Junfeng Ren, Guichao Hu and Shijie Xie, Organic Electronics 9 (2008) 687.
[15] P. A. Bobbert, T. D. Nguyen, F. W. A.van Oost, B. Koopmans and M.Wohlgenannt, Phys.Rev.Lett. 99,216801 (2007).
[16] T. L. Francis, O. Mermer, G. Veeraraghavan and M. Wohlgenannt, New Journal of Physics 6, 185(2004)
[17] T. D. Nguyen, Y. Sheng, J. Rybicki, and M. Wohlgenannt, Phys. Rev. B, 77, 235209 (2008)
[18] O. Mermer, G. Veeraraghavan, T. L. Francis and M. Wohlgenannt, Solid State Commun. 134,631(2005).
[19] Yuriy V. Pershin and Vlandimir Privman, Phys. Rev. Lett. 90, 256602 (2003).
[20] Z. G. Yu and M. E. Flatte, Phys. Rev. B. 66, 235302 (2002).
[21] R. A. Street, A. Salleo, and M. L. Chabinyc, Phys. Rev. B. 68, 085316 (2003).
[22] A. Salleo and R. A. Street, Phys. Rev. B. 70, 235324 (2004).
[1]See,e.g.,I.H.Campbell and D.L.Smith,Solid State Phys.55,1(2001).
[2]R.H.Friend,R.W.Gymer,A.B.Holmes,et al.,Nature 397,121(1999).
[3]D.Voss,Nature 407,442(2000).
[4]S.A.Wolf,D.D.Awschalom,R.A.Buhrman J.M.Daughton,S.von Molnar,M.L.Roukes,A.Y.Chtchelkanova,and D.M.Treger,Science 294,1488(2001).
[5]V.Dediu,M.Murgia,F.C.Matacotta,C.Taliani,and S.Barbanera,Solid State Comm.122,181(2002).
[6]Z.H.Xiong,Di Wu,Z.Valy Vardeny,and Jing Shi,Nature 427,821(2004).
[7] Sayani Majumdar, R. Laiho, P. Laukkanen, I. J. Vayrynen, Himadi S. Majumdar and R. Osterbacka, Appl. Phys. Lett. 89,122114 (2006).
[8] Z. G. Yu, M. A. Berding, and S. Krishnamurthy, Phys. Rev. B. 71, 060408R (2005).
[9] S. J. Xie, K. H. Ahn, D. L. Smith, A. R. Bishop, and A. Saxena, Phys. Rev. B. 67, 125202 (2003).
[10] Z. G. Yu, M. A. Berding, and S. Krishnamurthy, J. Appl. Phys. 97, 024510 (2005).
[11] J. F. Ren, J. Y. Fu, D. S. Liu, L. M. Mei, and S. J. Xie, J. Appl. Phys. 98, 074503 (2005).
[12] J. F. Ren, J. Y. Fu, D. S. Liu, L. M. Mei, and S. J. Xie, J. Phys.: Condens. Matter 17, 2341 (2005).
[13] A. Saxena, T. Castan, A. Planes, M. Porta, Y. Kishi, T. A. Lograsso, D. Viehland, M. Wuttig, and M. De Graef, Phys. Rev. Lett. 92, 197203 (2004).
[14] Yubin Zhang, Junfeng Ren, Guichao Hu and Shijie Xie, Organic Electronics 9, 687 (2008).
[15] S. T. Lee, Z. Q. Gao and L. S. Hung, Appl. Phys. Lett. 75,1404 (1999).
[16] C. Chao, K. Chuang, and S. Chen, Appl. Phys. Lett. 69, 2894 (1996).
[17] Junqing Zhao, Shijie Xie, Shenghao Han, Zhiwei Yang, Lina Ye and Tianlin Yang, Synthetic Metals 114,251 (2000).
[18] A. R. Schlatmann, D. wilms Floet, A. Hilberer, F. Garten, P. J. M. Smulders, T. M. Klapwijk and G. Hadziioannou, Appl. Phys. Lett. 69,1764 (1996).
[19] F. J. Wang, C. G. Yang, Z. Valy Vardeny and X. G. Li, Phys. Rev. B. 75,245324 (2007).
[20] Shinichi Tanabe, Shinji Miwa, Masaki Mizuguchi, Teruya Shinjo, Yoshishige Suzuki, and Masashi Shiraishi, Appl. Phys. Lett. 91,063123 (2007).
[21] Eun-Cheol Lee and K. J. Chang, Phys. Rev. B. 69, 085205 (2004).
[22] Yuriy V. Pershin and Vlandimir Privman, Phys. Rev. Lett. 90,256602 (2003).
[23] Z. G. Yu and M. E. Flatte, Phys. Rev. B. 66,235302 (2002).
[24] M. B. Prince, Phys. Rev. 92, 681 (1953).
[25] S. Pramanik, C-G Stefanita, S. Bandyopadhyay, N. Harth, K. Garre, and M. Cahay, arXiv:cond-mat/0508744.
[26] Julliere, Phys. Lett. A 54,225 (1975).
[27] R. J. Soilen, Jr., J. M. Byers, M. S. Osofsky, B. Nadgorny, T. Ambrose, S.F. Cheng, P. R. Broussard, C. T. Tanaka, J. Nowak, J. S. Moodera, A.Barry, and J. M. D. Coey, Science 282, 85 (1998).
[28] Yaohua Liu, Shannon M. Watson, Taegweon Lee, Justin M. Gorham, Howard E. Katz, Julie A. Borchers, Howard D. Fairbrother, and Daniel H. Reich, arXiv:0810.0289.
[29] P. P. Ruden and D. L. Smith, J. Appl. Phys. 95 (2004) 4898.
[30] J. D. Albrecht and D. L. Smith, Phys. Rev. B. 66,113303 (2002).
[31] M. Julliere, Phys. Lett. 54, 225-226 (1975)
[2] Baibich M N, et al. Phys. Rev. Lett., 61: 2472 (1988)
[3] Bamas J, et al. Phys. Rev. B, 42: 8110 (1990)
[4] Wolf S A, et al. Science, 294: 1488 (2001)
[5] Igor zutic, Jaroslav Fabian, S. Das Sarma, Rev. Mod. Phys., 76: 323 (2004)
[6] Meservey R, Phys. Rev. Lett., 25: 1270 (1970)
[7] Johnson M, Silsbee R H, Phys. Rev. Lett, 55:1790 (1985)
[8] Monzon F G, Tang H X, Roukes M L, Phys. Rev. Lett, 84: 5022 (2000)
[9] Ohno Y, et al. Nature, 402: 790 (1999)
[10] Datta S, Das B, Appl. Phys. Lett, 56 (7): 665 (1990)
[11] Chen C D, et al. Phys. Rev. Lett, 88: 047004 (2002)
[12] Julliere M, Phys. Lett. 54,225-226 (1975)
[13] Johnson M, and R. H. Silsbee, Phys. Rev. Lett. 55,1790-1793 (1985)
[14] Johnson M, and R. H. Silsbee, Phys. Rev. Lett. 60, 377 (1988)
[15] Mott N. F, Proc. R. Soc. London, Ser. A153, 699-717 (1936)
[16] Fert A, and I. A. Campbell, Phys. Rev. Lett. 21,1190-1192 (1968)
[17] Z. G. Yu and M. E. Flatte Phys. Rev. B. 66,235302 (2002).
[18] E. I. Rashba, Phys. Rev. B. 62, R16267 (2000).
[19] D. L. Smith and R. N. Silver, Phys. Rev. B. 64, 045323 (2001).
[20] A. Fert and H. Jaffres, Phys. Rev. B. 64,184420 (2002).
[21] S. Agrawal, M. B. A. Jalil, K. L. Teo, and Y. F. Liew, J. Appl. Phys. 97,103907 (2005)
[22] J. D. Albrecht and D. L. Smith, Phys. Rev. B. 66,113303, (2002).
[23] Karsten Flensberg, Thomas Stibius Jensen, and Niels Asger Mortensen, Phys. Rev. B. 64, 245308, (2001).
[24] J-Ph Ansermet, J. Phys.: Condens. Matter 10, 6027-6050 (1998)
[25] D'yakonov, M. I, and V. I. Perel', 1971e, Fiz. Tverd. Tela 13, 3581-3585 [Sov. Phys. Solid State 13, 3023-3026 (1971)]
[26] D'yakonov, M. I., and V. I. Perel', 1973b, "Optical orientation in a system of electrons and lattice nuclei in semiconductors Theory," Zh. Eksp. Teor. Fiz. 38, 362-376 [Sov. Phys. JETP 38,177-183 (1973)].
[27] Elliott, R. J., Phys. Rev. 96,266-279 (1954)
[28] Yafet, Y., J. Phys. Chem. Solids 21,99-104 (1961)
[29] Bir, G. L., A. G. Aronov, and G. E. Pikus, 1975, "Spin relaxation of electrons due to scattering by holes," Zh. Eksp. Teor. Fiz. 69, 1382-1397 [Sov. Phys. JETP 42, 705-712 (1976)].
[30] Ito T , Sh irakaw a H, Ikeda S. Simultaneous polymerization and format ion of polyacetylene film on the surface of concent rated so luble Ziegler2Type catalyst solution. J Polym Sci Polym Chem, 1974; 12: 11
[31] C. K. Chang, C. R. Fincher, Y. W. Park, et al, Phys. Rev. Lett 39 1098 (1977)
[32] W. P. Su, J. R. Schrieffer, and A. J. Heeger, Phys. Rev. Lett. 42,1698 (1979) Su W P, Sch rieffer J , Heeger A J. Solitons in polyacetylene. Phys Rev Lett, 1979; 42: 1698
[33] C. K. Chang, E. J. Louis, M. A. Druy et al, J Am Chem Soc 100 1013 (1978)
[34] R. L. Greene et al, Phys. Rev. Lett 34 577 (1975)
[35] Y. Park et al, J. Chem. Phys 73 946 (1980)
[36] H. Naarmann, N. Theophilou, Synth Met 22 1 (1987)
[37] W. J. Feast, J. Tsibouklis, K. L. Pouwer, L. Gronendaal, and E. W. Meijer, Polymer 37 5017(1996)
[38] Schon J H, Berg S, Kloc Ch, et al. Ambipolar pentacene field effect transistors and inverters. Science, 287,1022 (2000)
[39] Jurchescu O D, Baas J and Palstra T T M, Appl. Phys. Lett. 84 3061 (2004)
[40] Rajca A, et al. Science, 2001,294: 1503
[41] Miller J S, et al. Chem Rev, 1988, 88: 201
[42] T. L. Makarova, B. Sundqvist, et al. Nature 413, 716 (2001)
[43] Y. V. Korshak, T. V. Medvedeva, A. A. Ovchinnikov, and V. N. Spector, Nature 326,370(1987)
[44] M. Takahashi, P. Turk, Y. Nakazawa, M. Tamura, K. Nozawa, D. Shioni, M. Ishikawa and M. Kinoshita, Phys. Rev. Lett. 67, 746 (1991)
[45] A. A. Ovchinnikov and V. N. Spector, Synth Met. 27, 615 (1988)
[46] Z. Fang, Z. L. Liu, and K. L. Yao, Phys. Rev. B 49, 3916 (1994)
[47] Z. Y. Sun, K. L. Yao, W. Yao, D. H. Zhang, and Z. L. Liu, Phys. Rev. B 77, 014416(2008).
[48] Tang CW , VanSlyke S A. Organic electroluminescent diodes. ApplPhys Lett, 1987; 51: 913
[49] Burroughes J H, Bradley D D C, Brown A R, et al. Light-emitting diodes based on conjugated polymers. Nature, 1990; 347: 539
[50] J. H. Burroughes, D. D C Bradley, A R Brown et al, Nature 347 539(1990)
[51] Z. Yang, I Sokolik, F. E Karasz, Macromolecules 26 1188(1993)
[52] E. G. J Staring, R C J E Demandt, D Braun et al, Adv Mater 6 488(1994)
[53] N. C. Greenham, S C Mora tti, D D C, et al, Nature 365 628(1993)
[54] Voss D, Nature, 2000, 442: 407
[55] R. H. Friend, R. W Gymer, A. B.Holmes, J. H. Burroughes, R. N. Marks, C. Taliani, D. D. C. Bradley, D. A. Santos, J. L.Bre'das, M. Logdlund, W. R. Salaneck, Nature 397 121(1999)
[56] D. Braun, A. J. Heeger, Appl. Phys. Lett 58 1982(1991)
[57] Z. L. Shen, P. E.Burrows, V. Bulovic, S. R. Forrest, M. E. Thompson, Science 276 2009; 78 729(1997)
[58] H. Sirringhaus, N. Tessler, R. H. Friend, Science 280,1741(1998)
[59] P. K. H. Ho, D. S. Thomas, R. H. Friend, N. Tessler, Science 285 233(1999)
[60] A. odabalapur, Z. ao, A. akhija, J. G. aquindanum, V. R. Raju, Y. Feng, H. E. Katz, J. Rogers, Appl. Phys. Lett 73 142; 32 267(1998)
[61] C. K. Chang, C. R. Fincher, Y. W. Park, A. J. Heeger, H. Shirakawa, E. J. Louis, S. C. Gau, and A. G. MacDiarmid, Phys. Rev. Lett. 39,1098-1101 (1977)
[62] C. K. Chiang, M. A. Druy, S. C. Gau, A. J. Heeger, E. J. Louis, A. G. MacDiarmid, Y. W. Park, and H. Shirakawa, J. Am. Chem. Soc. 100,1013 (1978)
[63] W. P. Su, J. R. Schrieffer, and A. J. Heeger, Phys. Rev. 22,2099 (1980)
[64] P. E. Peierls, Quantum Theory of Solids, Oxford University Press, London, 1955, 108
[65] 孙鑫 物理学进展 6, 1 (1986).
[66] V. Dediu, M. Murgia, F. C. Matacotta, C. Taliani, and S. Barbanera, Solid State Comm. 122,181 (2002).
[67] Xiong Z H, et al. Nature, 2004,427: 821
[68] T. S. Santos, J. S. Lee, P. Migdal, I. C. Lekshmi, B. Satpati, and J. S. Moodera, Phys. Rev. Lett. 98, 016601 (2007)
[69] M. Ouyang and D. D. Awschalom, Science 301, 1074 (2003)
[70] J. R. Petta, S. K. Slater, and D. C. Ralph, Phys. Rev. Lett. 93,136601 (2004)
[71] A. N. Pasupathy, R. C. Bialczak, J. Martinek, J. E. Grose, L. A. K. Donev, P. L. McEuen and D. C. Ralph, Science 306,86 (2004).
[72] T. L. Francis, O. Mermer, G. Veeraraghavan and M. Wohlgenannt, New Journal of Physics 6,185(2004)
[73] T. D. Nguyen, Y. Sheng, J. Rybicki, and M. Wohlgenannt, Phys. Rev. B, 77, 235209 (2008)
[74] O. Mermer, G. Veeraraghavan, T. L. Francis and M. Wohlgenannt, Solid State Commun. 134,631(2005).
[75] P. A. Bobbert, T. D. Nguyen, F. W. A.van Oost, B. Koopmans and M. Wohlgenannt, Phys.Rev.Lett. 99,216801 (2007).
[76] Li S, Chen L S, George T H, Sun X, Phys. Rev. B, 2004, 70: 075201.
[77] Zwolak M, Di Ventra M, Appl. Phys. Lett., 2002, 81: 925.
[78] S. J. Xie, K. H. Ahn, D. L. Smith, Phys. Rev. B, 2003, 67: 125202.
[79] J. Y. Fu, J. F. Ren, et al. Thin Solid Films 477 (2005) 212.
[80] J. Y. Fu, J. F. Ren, et al. Synthetic Metal 156 (2006) 370
[81] J. Y. Fu, J. F. Ren, X. J. Liu, D. S. Lie and S. J. Xie, Phys. Rev. B 73, 195401 (2006).
[82] J. Lei, H. Li, S. Yin and S. J. Xie, J. Phys. C 20, 095201 (2008).
[83] C. Toher and S. Sanvito, Phys. Rev. Lett. 99, 056801 (2007).
[84] E. G. Emberlya, G. Kirczenow, Chem. Phys. 281, 311 (2002).
[83]R.Pati,L.Senapati,P.M.Ajayan,and S.K.Nayak,Phys.Rev.B 68,100407(2006).
[86]D.Waldron,P.Haney,B.Larade,A.MacDonald,and H.Guo,Phys.Rev.Lett.96,166804(2006).
[87]J.H.Wei,S.J.Xie,L.M.Mei,J.Berakdar,and Y.J.Yan,New J.Phys.8,82(2006).
[88]J.H.Wei,S.J.Xie,L.M.Mei,J.Berakdar,and Y.J.Yan,Org.Electron.8,487(2007).
[89]R.Liu,S.Ke,H.U.Baranger and W.Yang,Nano Letters 5,1959(2005).
[90]H.Dalgleish and G.Kirczenow,Phys.Rev.B 73,235436(2006).
[91]P.P.Ruden and D.L.Smith,J.Appl.Phys.95,4898(2004).
[92]Z.G.Yu,M.A.Berding,and S.Krishnamurthy,Phys.Rev.B.71,060408(2005).
[93]Z.G.Yu,M.A.Berding,and S.Krishnamurthy,J.Appl.Phys.,97,024510(2005).
[94]J.F.Ren,et al.J.Appl.Phys.,2005,98:074503.
[95]J.F.Ren,J.Y.Fu,et al.J.Phys.:Condens.Matter 17(2005) 2341.
[96]Yubin Zhang,Junfeng Ren,Guichao Hu and Shijie Xie,Organic Electronics 9(2008) 687.
[97]Yubin Zhang,Junfeng Ren,Jie Lei,Shijie Xie,Organic Electronics,doi:10.1016/j.orgel.2009.02.005.
[98]R.A.Street,A.Salleo,and M.L.Chabinyc,Phys.Rev.B.68,085316(2003).
[99]P.A.Bobbert,T.D.Nguyen et al.Phys.Rev.Lett.99,216801(2007).
[100]任俊峰,付吉永,解士杰,物理(约稿),第35卷第10期,852-859(2006)
[101]任俊峰,付吉永,刘德胜,解士杰,物理学报,第53卷第11期,3814-3817(2004)
[102]J.F.Ren,J.Y.Fu,D.S.Liu,L.M.Mei,S.J.Xie,Synthic Metal 155,611-614(2005)
[103]任俊峰,张玉滨,解士杰,物理学报,第56卷第8期,4785-4790(2007)
[104]Junfeng Ren,Yubin Zhang,Shijie Xie,Organic Electronics 9,1017-1021(2008)
[105] Y. N. Ma, J. F. Ren, Y. B. Zhang, D. S. Liu, S. J. Xie, Chin. Phys. Lett. 24, 1697-1700(2007)
[106] Guichao Hu, Ying Guo, Jianhua Wei, and Shijie Xie, Phys. Rev. B 75, 165321 (2007)
[107] Guichao Hu, Keliang He, Shijie Xie, and Avadh Saxena, J. Chem. Phys. 129, 234708 (2008)
[1]半导体物理学,上册,叶良修 高等教育出版社,1983
[2]半导体物理学,刘恩科 朱秉生 罗晋生 西安交通大学出版社,1998
[3]Z.G.Yu and M.E.Flatte,Phys.Rev.B 66,235302(2002)
[4]Y.V.Pershin and V.Privman,Phys.Rev.Lett.90,256602(2003)
[5]Z.G.Yu and M.E.Flatte,Phys.Rev.B 66,201202(R)(2002)
[6]E.I.Rashba,Phys.Rev.B.62,R16267(2000).
[7]I.Zutic,J.Fabian,and S.Das Sarmal,Phys.Rev.Lett.88,066603(2002)
[8]Ivar Martin,Phys.Rev.B 67,014421(2003)
[1]See,e.g.,I.H.Campbell and D.L.Smith,Solid State Phys.55,1(2001).
[2]R.H.Friend,R.W.Gymer,A.B.Holmes,et al.,Nature 397,121(1999).
[3]S.Forrest,P.Burrows,and M.Thompson,IEEE Spectr.37,29(2000).
[4]D.Voss,Nature 407,442(2000).
[5]S.A.Wolf,D.D.Awschalom,R.A.Buhrman J.M.Daughton,S.von Molnar,M.L.Roukes,A.Y.Chtchelkanova,and D.M.Treger,Science 294,1488(2001).
[6]V.Dediu,M.Murgia,F.C.Matacotta,C.Taliani,and S.Barbanera,Solid State Comm.122,181(2002).
[7]Z.H.Xiong,Di Wu,Z.Valy Vardeny,and Jing Shi,Nature 427,821(2004).
[8]Sayani Majumdar,R.Laiho,P.Laukkanen,I.J.V(a)yrynen,Himadi S.Majumdar and R.(O|¨)sterbacka,Appl.Phys.Lett.89,122114(2006).
[9]Z.G.Yu,M.A.Berding,and S.Krishnamurthy,Phys.Rev.B.71,060408R (2005).
[10]S.J.Xie,K.H.Ahn,D.L.Smith,A.R.Bishop,andA.Saxena,Phys.Rev.B.67,125202(2003).
[11]D.L.Smith and R.N.Silver,Phys.Rev.B.64,045323(2001)
[12]P.P.Ruden and D.L.Smith,J.Appl.Phys.95,4898(2004).
[13]Z.G.Yu,M.A.Berding,and S.Krishnamurthy,J.Appl.Phys.97,024510(2005).
[14]J.F.Ren,J.Y.Fu,D.S.Liu,L.M.Mei,and S.J.Xie,J.Appl.Phys.98,074503(2005).
[15]J.F.Ren,J.Y.Fu,D.S.Liu,L.M.Mei,and S.J.Xie,J.Phys.:Condens.Matter 17,2341 (2005).
[16] A. Saxena, T. Castan, A. Planes, M. Porta, Y. Kishi, T. A. Lograsso, D. Viehland, M. Wuttig, and M. De Graef, Phys. Rev. Lett. 90,197203 (2004).
[17] M. J. Nowak, D. Spiegel, S. Hotta. A. J. Heeger, and P. A. Pincus, Macromolecules 22,2917 (1989).
[18] Matheus Paes Lima and Geraldo Magela e Silva, Phys. Rev. B. 74,224304 (2006)
[19] Shi-jie Xie, Liang-mo Mei, and D. L. Lin, Phys. Rev. B. 50,13364 (1994)
[20] Yuriy V. Pershin and Vlandimir Privman, Phys. Rev. Lett. 90,256602 (2003).
[21] R. A. Street, A. Salleo, and M. L. Chabinyc, Phys. Rev. B. 68, 085316 (2003).
[22] A. Salleo and R. A. Street, Phys. Rev. B. 70, 235324 (2004).
[23] Z. G. Yu and M. E. Flatte, Phys. Rev. B. 66, 235302 (2002).
[24] T. C. Chung, J. H. Kaufman, A. J. Heeger, and F. Wudl, Phys. Rev. B. 30, 702 (1984).
[25] K. E. Ziemelis, A. T. Hussain, D. D. C. Bradley, R. H. Friend, J. Ruhe, and G. Wegner, Phys. Rev. Lett. 66,2231 (1991)
[1] P. P. Ruden and D. L. Smith, J. Appl. Phys. 95,4898 (2004).
[2] Z. G. Yu, M. A. Berding, and S. Krishnamurthy, J. Appl. Phys. 97, 024510 (2005).
[3] Z. G. Yu, M. A. Berding, and S. Krishnamurthy, Phys. Rev. B. 71, 060408 (2005).
[4] S. J. Xie, K. H. Ahn, D. L. Smith, A. R. Bishop, and A. Saxena, Phys. Rev. B. 67, 125202 (2003).
[5] A. J. Heeger, S. Kivelson, J. R. Schrieffer, and W. P. Su, Rev. Mod. Phys. 60, 781 (1988).
[6] P. S. Davids, A. Saxena, and D. L. Smith, J. Appl. Phys. 78,4244 (1995).
[7] Geraldo Magela e Silva, Phys. Rev. B. 61,10777 (2000).
[8] J. C. Scott, P. Pfluger, M. T. Krounbi, and G. B. Street, Phys. Rev. B. 28,2140 (1983).
[9] F. Genoud, M. Guglielmi, M. Nechtschein, E. Genies, and M. Salmon, Phys. Rev. Lett. 55,118(1985)
[10] J. F. Ren, J. Y. Fu, D. S. Liu, L. M. Mei, and S. J. Xie, J. Appl. Phys. 98, 074503 (2005).
[11] D. L. Smith and R. N. Silver, Phys. Rev. B. 64, 045323 (2001)
[12] J. F. Ren, J. Y. Fu, D. S. Liu, L. M. Mei, and S. J. Xie, J. Appl. Phys. 98, 074503 (2005).
[13] J. F. Ren, J. Y. Fu, D. S. Liu, L. M. Mei, and S. J. Xie, J. Phys.: Condens. Matter 17,2341 (2005).
[14] Yubin Zhang, Junfeng Ren, Guichao Hu and Shijie Xie, Organic Electronics 9 (2008) 687.
[15] P. A. Bobbert, T. D. Nguyen, F. W. A.van Oost, B. Koopmans and M.Wohlgenannt, Phys.Rev.Lett. 99,216801 (2007).
[16] T. L. Francis, O. Mermer, G. Veeraraghavan and M. Wohlgenannt, New Journal of Physics 6, 185(2004)
[17] T. D. Nguyen, Y. Sheng, J. Rybicki, and M. Wohlgenannt, Phys. Rev. B, 77, 235209 (2008)
[18] O. Mermer, G. Veeraraghavan, T. L. Francis and M. Wohlgenannt, Solid State Commun. 134,631(2005).
[19] Yuriy V. Pershin and Vlandimir Privman, Phys. Rev. Lett. 90, 256602 (2003).
[20] Z. G. Yu and M. E. Flatte, Phys. Rev. B. 66, 235302 (2002).
[21] R. A. Street, A. Salleo, and M. L. Chabinyc, Phys. Rev. B. 68, 085316 (2003).
[22] A. Salleo and R. A. Street, Phys. Rev. B. 70, 235324 (2004).
[1]See,e.g.,I.H.Campbell and D.L.Smith,Solid State Phys.55,1(2001).
[2]R.H.Friend,R.W.Gymer,A.B.Holmes,et al.,Nature 397,121(1999).
[3]D.Voss,Nature 407,442(2000).
[4]S.A.Wolf,D.D.Awschalom,R.A.Buhrman J.M.Daughton,S.von Molnar,M.L.Roukes,A.Y.Chtchelkanova,and D.M.Treger,Science 294,1488(2001).
[5]V.Dediu,M.Murgia,F.C.Matacotta,C.Taliani,and S.Barbanera,Solid State Comm.122,181(2002).
[6]Z.H.Xiong,Di Wu,Z.Valy Vardeny,and Jing Shi,Nature 427,821(2004).
[7] Sayani Majumdar, R. Laiho, P. Laukkanen, I. J. Vayrynen, Himadi S. Majumdar and R. Osterbacka, Appl. Phys. Lett. 89,122114 (2006).
[8] Z. G. Yu, M. A. Berding, and S. Krishnamurthy, Phys. Rev. B. 71, 060408R (2005).
[9] S. J. Xie, K. H. Ahn, D. L. Smith, A. R. Bishop, and A. Saxena, Phys. Rev. B. 67, 125202 (2003).
[10] Z. G. Yu, M. A. Berding, and S. Krishnamurthy, J. Appl. Phys. 97, 024510 (2005).
[11] J. F. Ren, J. Y. Fu, D. S. Liu, L. M. Mei, and S. J. Xie, J. Appl. Phys. 98, 074503 (2005).
[12] J. F. Ren, J. Y. Fu, D. S. Liu, L. M. Mei, and S. J. Xie, J. Phys.: Condens. Matter 17, 2341 (2005).
[13] A. Saxena, T. Castan, A. Planes, M. Porta, Y. Kishi, T. A. Lograsso, D. Viehland, M. Wuttig, and M. De Graef, Phys. Rev. Lett. 92, 197203 (2004).
[14] Yubin Zhang, Junfeng Ren, Guichao Hu and Shijie Xie, Organic Electronics 9, 687 (2008).
[15] S. T. Lee, Z. Q. Gao and L. S. Hung, Appl. Phys. Lett. 75,1404 (1999).
[16] C. Chao, K. Chuang, and S. Chen, Appl. Phys. Lett. 69, 2894 (1996).
[17] Junqing Zhao, Shijie Xie, Shenghao Han, Zhiwei Yang, Lina Ye and Tianlin Yang, Synthetic Metals 114,251 (2000).
[18] A. R. Schlatmann, D. wilms Floet, A. Hilberer, F. Garten, P. J. M. Smulders, T. M. Klapwijk and G. Hadziioannou, Appl. Phys. Lett. 69,1764 (1996).
[19] F. J. Wang, C. G. Yang, Z. Valy Vardeny and X. G. Li, Phys. Rev. B. 75,245324 (2007).
[20] Shinichi Tanabe, Shinji Miwa, Masaki Mizuguchi, Teruya Shinjo, Yoshishige Suzuki, and Masashi Shiraishi, Appl. Phys. Lett. 91,063123 (2007).
[21] Eun-Cheol Lee and K. J. Chang, Phys. Rev. B. 69, 085205 (2004).
[22] Yuriy V. Pershin and Vlandimir Privman, Phys. Rev. Lett. 90,256602 (2003).
[23] Z. G. Yu and M. E. Flatte, Phys. Rev. B. 66,235302 (2002).
[24] M. B. Prince, Phys. Rev. 92, 681 (1953).
[25] S. Pramanik, C-G Stefanita, S. Bandyopadhyay, N. Harth, K. Garre, and M. Cahay, arXiv:cond-mat/0508744.
[26] Julliere, Phys. Lett. A 54,225 (1975).
[27] R. J. Soilen, Jr., J. M. Byers, M. S. Osofsky, B. Nadgorny, T. Ambrose, S.F. Cheng, P. R. Broussard, C. T. Tanaka, J. Nowak, J. S. Moodera, A.Barry, and J. M. D. Coey, Science 282, 85 (1998).
[28] Yaohua Liu, Shannon M. Watson, Taegweon Lee, Justin M. Gorham, Howard E. Katz, Julie A. Borchers, Howard D. Fairbrother, and Daniel H. Reich, arXiv:0810.0289.
[29] P. P. Ruden and D. L. Smith, J. Appl. Phys. 95 (2004) 4898.
[30] J. D. Albrecht and D. L. Smith, Phys. Rev. B. 66,113303 (2002).
[31] M. Julliere, Phys. Lett. 54, 225-226 (1975)