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巨磁电阻效应的发现开拓了磁电子学的新领域,20世纪90年代,磁电子学到了迅速的发展,并在实际应用方面取得了显著的经济效益与巨大的社会效益,本世纪初,研究重点已转移到新的半导体自旋电子学方向,并取得了重要进展。本文结合作者率领的科研组的研究工作,阐述了从磁电子学材料到半导体自旋电子学材料的发展概况,其中,重点介绍了稀磁半导体材料的研究进展。 相似文献
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以氧化物宽禁带半导体为基体,通过掺杂磁性元素,可将非磁性半导体转变成铁磁性半导体,利用这些铁磁性半导体,能将新型的自旋电子器件集成到传统的微电子器件上,构成功能丰富的新型器件.由于稀磁半导体材料在自旋电子学中的重要作用,近年来受到广泛的关注.简要总结了有关氧化物稀磁半导体研究的发展状况;分析了制备条件对其磁性的可能影响;重点介绍了该系统中有关磁性起源的理论模型,包括双交换机制、磁极化子模型、RKKY模型等;比较了2种磁极化子理论模型,并对这些模型的适用范围进行了分析讨论.另外,还介绍了该体系微结构和磁结构的一些检测方法以及与磁性相关的输运性质、反常霍尔效应等. 相似文献
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自旋电子学是目前固体物理和电子学中的一个“热点”,其中心议题是利用和控制固体,尤其是半导体中的自旋自由度。本主要内容是:1、MBE生长的Ⅲ-Ⅴ族基铁电薄膜和异质结构,2、具有高铁磁转变温度的Mm6掺杂的GaAs/P-A1GaAs异质结及与自旋相关性质的控制,3、Si基自旋电子学。 相似文献
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锰氧化物LaSrMnO系列材料是一类有用的自旋电子学材料。La0.5Sr0.5MnO3是一种铁磁金属性材料。利用了在La位掺杂Y的方法来改变La0.5Sr0.5MnO3的金属性而保持它的铁磁性。通过样品输运和磁化强度等的测量对La0.45Y0.05Sr0.5MnO3样品的物性进行了研究,获得了居里温度Tc=292K的亚铁磁半导体样品。 相似文献
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I. A. Buyanova W. M. Chen A. A. Toropov S. V. Sorokin S. V. Ivanov P. S. Kop''ev 《Journal of Superconductivity》2003,16(2):399-402
Strong effect of structural design on spin functionality is observed in quantum structures based on II–VI semiconductors. Spin switching is realized when using a thin layer of Zn0.95Mn0.05Se diluted magnetic semiconductor (DMS) as a spin manipulator. This is evident from the polarization of photoluminescence related to a spin detector (an adjacent nonmagnetic quantum well (QW)) measured under the resonant excitation of the spin-up and spin-down states of the DMS, which is identical in value but opposite in sign. The achieved spin switching is suggested to reflect fast carrier diffusion from the DMS due to the absence of an energy barrier between the upper spin state of the DMS layer and the QW. On the other hand, the spin alignment is accomplished in the tunneling structures where the presence of the energy barrier inserted between a spin manipulator (i.e., a ZnMnSe/CdSe DMS superlattice) and a spin detector ensures a slow escape rate from the DMS layer. 相似文献
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Semiconductor nanostructures show many special physical properties associated with quantum confinement effects, and have many applications in the opto-electronic and microelectronic fields. However, it is difficult to calculate their electronic states by the ordinary plane wave or linear combination of atomic orbital methods. In this paper, we review some of our works in this field, including semiconductor clusters, self-assembled quantum dots, and diluted magnetic semiconductor quantum dots. In semiconductor clusters we introduce energy bands and effective-mass Hamiltonian of wurtzite structure semiconductors, electronic structures and optical properties of spherical clusters, ellipsoidal clusters, and nanowires. In self-assembled quantum dots we introduce electronic structures and transport properties of quantum rings and quantum dots, and resonant tunneling of 3-dimensional quantum dots. In diluted magnetic semiconductor quantum dots we introduce magnetic-optical properties, and magnetic field tuning of the effective g factor in a diluted magnetic semiconductor quantum dot. 相似文献
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Takuro Tomita Ayahito Uetake Tsutomu Asahina Kentaro Kayanuma Akihiro Murayama Yasuo Oka 《Journal of Superconductivity and Novel Magnetism》2005,18(3):405-410
Spin injection processes in the double quantum dots of ZnSe-based diluted magnetic semiconductors are discussed. Double quantum
dots are fabricated from ZnSe-based double quantum wells by electron beam lithography and wet etching. In these samples, the
photo-excited carriers in the magnetic dots are injected into the non-magnetic dots. The circular polarization degrees of
photoluminescence from the non-magnetic dots are measured by micro-photoluminescence measurement system under the magnetic
field up to 5 T. The maximum spin polarization degrees of injected carriers determined from our experiment are 10% for double
quantum wells and 15% for double quantum dots. The spin injection efficiency was estimated both from the observed circular
polarization degree and the diffusion length of carriers. We concluded that the spin injection efficiency is increased in
the double quantum dots. 相似文献
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We provide an overview of measurements that elucidate the effects of interactions, quantum confinement, reduced dimensionality, and interfacial geometries on coherent electronic spin dynamics and spin transport in doped semiconductors. The experiments focus on a variety of doped semiconductor systems, ranging from bulk n-GaAs crystals to modulation doped II-VI magnetic semiconductor quantum wells. In particular, the latter provide model systems in which electron gases are strongly exchange-coupled to an engineered distribution of magnetic moments, hence allowing one to systematically tailor spin interactions between confined electronic states, magnetic ions, and nuclei. Two complementary techniques including state-of-the-art spin dynamical probes having high temporal (~100 fs) and spatial (~100 nm) resolution, and low-temperature magneto-transport, are used to survey a variety of physical phenomena in these systems. 相似文献
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《Materials Science & Technology》2013,29(8):823-845
Phosphorus donor spins in silicon are promising quantum bit (qubit) candidates. They have a natural confinement potential, long spin lifetimes and decades of use in the semiconductor fabrication industry. Readout of a single qubit is a necessary step to build a quantum computer, which could potentially solve particular problems exponentially faster than conventional computers. Electrically detected magnetic resonance has previously been used to measure the spin state of an ensemble of spins. In this literature review, the concept of a quantum computer is introduced before the potential of using electrically detected magnetic resonance to measure the spin state of a single donor spin qubit in a silicon transistor is discussed. 相似文献
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Gang JI Shishen YAN Yanxue CHEN Qiang CAO Wei XIA Yihua LIU Liangmo MEI Ze ZHANG 《材料科学技术学报》2008,24(3):415-418
2x (FeNi/CoZnO)/ZnO/(CoZnO/Co) x2 spin-inJection devices were prepared by sputtering and photo-lithography. In the devices, two composite magnetic layers 2x(FeNi/CoZnO) and (CoZnO/Co)x2 with different coercivities were used to fabricate the ZnO-based semiconductor spin valve. Since the CoZnO ferromagnetic semiconductor layers touched the ZnO space layer directly, the significant spin injection from CoZnO into ZnO was observed by measuring the magnetoresistance of the spin-injection devices. The magnetoresistance reduced linearly with increasing temperature, from 1.12% at 90 K to 0.35% at room temperature. 相似文献
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Controlling and monitoring individual spins is desirable for building spin-based devices, as well as implementing quantum information processing schemes. As with trapped ions in cold gases, magnetic ions trapped on a semiconductor lattice have uniform properties and relatively long spin lifetimes. Furthermore, diluted magnetic moments in semiconductors can be strongly coupled to the surrounding host, permitting optical or electrical spin manipulation. Here we describe the zero-field optical manipulation of a few hundred manganese ions in a single gallium arsenide quantum well. Optically created mobile electron spins dynamically generate an energy splitting of the ion spins and enable magnetic moment orientation solely by changing either photon helicity or energy. These polarized manganese spins precess in a transverse field, enabling measurements of the spin lifetimes. As the magnetic ion concentration is reduced and the manganese spin lifetime increases, coherent optical control and readout of single manganese spins in gallium arsenide should be possible. 相似文献
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Y. S. Chen S. Halm T. Kümmell G. Bacher M. Wiater T. Wojtowicz G. Karczewski 《Journal of Superconductivity and Novel Magnetism》2010,23(1):111-114
We present an approach to electrical control of the spin polarization in a diluted magnetic semiconductor (DMS) structure.
A variable magnetic field induced by a micro-scale current loop magnetizes the Mn2+ ions in a CdMnTe/CdMgTe DMS quantum well, which via the sp-d exchange interaction polarizes photo-generated electron-hole pairs confined in the well. A maximum spin polarization degree
of ±8.5% is obtained at 4.2 K without external magnetic field. The current-induced magnetic field and the current-generated
heating of the spin system are quantitatively extracted by micro magneto-luminescence measurements. 相似文献
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A. V. Akimov A. V. Scherbakov D. R. Yakovlev W. Ossau L. W. Molenkamp Y. Oka I. Souma Y. Terai S. Kuroda K. Takita 《Journal of Superconductivity》2003,16(2):391-394
We use the combination of nonequilibrium phonon and exciton luminescence techniques to study the spin dynamics in diluted magnetic semiconductor structures with (Cd,Mn)Te and (Cd,Mn)Se quantum dots (QDs). We show that the spin–lattice relaxation (SLR) of Mn ions in these structures differs strongly from the SLR in quantum wells. We explain the results by a model where SLR process in structures with QDs is modified by the spin diffusion on Mn ions from the QD to a wetting layer. 相似文献
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Makhonin MN Kavokin KV Senellart P Lemaître A Ramsay AJ Skolnick MS Tartakovskii AI 《Nature materials》2011,10(11):844-848
Highly polarized nuclear spins within a semiconductor quantum dot induce effective magnetic (Overhauser) fields of up to several Tesla acting on the electron spin, or up to a few hundred mT for the hole spin. Recently this has been recognized as a resource for intrinsic control of quantum-dot-based spin quantum bits. However, only static long-lived Overhauser fields could be used. Here we demonstrate fast redirection on the microsecond timescale of Overhauser fields on the order of 0.5 T experienced by a single electron spin in an optically pumped GaAs quantum dot. This has been achieved using coherent control of an ensemble of 10(5) optically polarized nuclear spins by sequences of short radiofrequency pulses. These results open the way to a new class of experiments using radiofrequency techniques to achieve highly correlated nuclear spins in quantum dots, such as adiabatic demagnetization in the rotating frame leading to sub-μK nuclear spin temperatures, rapid adiabatic passage, and spin squeezing. 相似文献