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1.
对磁量子结构中电子在外加恒定电场下的输运性质进行了研究.分别计算了电子隧穿相同磁垒磁阱和不同磁垒磁阱构成的两种磁量子结构的传输概率和电流密度.计算结果表明,在相当宽广的非共振电子入射能区,外加电场下电子的传输概率比无电场时增加.对于电子隧穿相同磁垒磁阱构成的双磁垒结构,共振减弱;对于电子隧穿不同磁垒磁阱构成的双磁垒结构,无电场作用时的非完全共振在适当的偏置电压下转化为完全共振,这时的电子可实现理想的共振隧穿.研究同时表明,磁量子结构中存在着显著的量子尺寸效应和负微分电导. 相似文献
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研究了与铁磁/半导体/铁磁结构相关的双量子环自旋输运的规律,研究结果表明:总磁通为零条件下,铁磁电极磁化方向反平行时,双量子环与单量子环相比提高了自旋电子透射概率的平均值.铁磁电极磁化方向平行时,双量子环对提高自旋向下电子平均透射概率的效果更明显;双量子环受到Rashba自旋轨道耦合作用影响时,自旋电子的平均透射概率明显高于单量子环,即使再加上外加磁场的影响,透射概率较高这一特征依然存在;双量子环所含的δ势垒具有阻碍自旋电子输运的作用,随δ势垒强度Z的增大透射概率
关键词:
双量子环
Rashba自旋轨道耦合
透射概率
δ势垒')" href="#">δ势垒 相似文献
4.
在有效质量近似条件下研究了由两个垂直耦合自组织InAs量子点组成的双电子量子点分子的电子结构,在此基础上利用系统的总自旋提出了一种磁场方向调制的量子比特方案.电子的相关效应可以导致系统的总自旋在0和1之间转换,值得注意的是,通过调节外部磁场的方向来实现这种转换,而不是像以往那样通过改变外部磁场的大小.结果支持利用系统的总自旋作为磁场方向调制的量子比特的可能性,而且因为高质量的垂直耦合量子点分子的制作工艺已经成熟,所以这是一个非常现实的量子比特设计方案.
关键词:
量子点分子
磁场方向调制
量子比特 相似文献
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半导体微结构的尺度可以与电子的相位相干长度相比较,在输运过程中,电子保持“相位记忆”,表现为量子弹道式输运和具有量子相干性.本文着重介绍在零磁场和磁场下,量子点接触微结构中的电子的量子弹道输运过程和电导呈现量子化现象.还介绍了由量子相干性输运导致的相干的电子聚焦现象 相似文献
6.
胡延梅 《原子与分子物理学报》2018,35(6)
最近研究发现石墨烯在一维周期性电学或磁学调制势下, 其扩散电导率会出现Weiss振荡. 本文进一步探索了面外加垂直磁场和面内加横向电场以及一维周期性弱调制电学势的多场耦合作用下, 石墨烯的量子磁输运性质, 结果表明: Weiss振荡振幅和电导率数值都随着静电场的增加而增加. 有趣的是, 当电场与磁场的比值达到某一临界值, 即时, 输运电导率的Weiss振荡突然消失. 这一奇特现象在传统的二维电子气体中是不存在的, 因此可以归因于石墨烯载流子外加电磁场的反常相对论性能谱.
关键词:石墨烯; 静电场; Weiss振荡; 磁输运性质 相似文献
7.
胡延梅 《原子与分子物理学报》2019,36(6)
最近研究发现石墨烯在一维周期性电学或磁学调制势下, 其扩散电导率会出现Weiss振荡. 本文进一步探索了面外加垂直磁场和面内加横向电场以及一维周期性弱调制电学势的多场耦合作用下, 石墨烯的量子磁输运性质, 结果表明: Weiss振荡振幅和电导率数值都随着静电场的增加而增加. 有趣的是, 当电场与磁场的比值达到某一临界值, 即时, 输运电导率的Weiss振荡突然消失. 这一奇特现象在传统的二维电子气体中是不存在的, 因此可以归因于石墨烯载流子外加电磁场的反常相对论性能谱.
关键词:石墨烯; 静电场; Weiss振荡; 磁输运性质 相似文献
8.
胡延梅 《原子与分子物理学报》2017,34(6):1123-1127
最近研究发现石墨烯在一维周期性电学或磁学调制势下,其扩散电导率会出现Weiss振荡.本文进一步探索了面外加垂直磁场和面内加横向电场以及一维周期性弱调制电学势的多场耦合作用下,石墨烯的量子磁输运性质,结果表明:Weiss振荡振幅和电导率数值都随着静电场的增加而增加.有趣的是,当电场与磁场的比值达到某一临界值,即β_1=E/(ν_F·B)=1时,输运电导率的Weiss振荡突然消失.这一奇特现象在传统的二维电子气体中是不存在的,因此可以归因于石墨烯载流子外加电磁场的反常相对论性能谱. 相似文献
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研究了电子的自旋相关的隧穿和极化。在外加磁场的作用下,自旋向上的电子与自旋向下的电子具有不同的隧穿系数。当电子的自旋方向与磁场方向相反时,其隧穿概率受到磁场的抑制而变小;反之,当两平行时,电子的了隧穿系数增大。这种差异可以用本中定义的自旋极化率来表示。本对不同磁场下的自旋极化率进行了计算,结果也表明当电子的动能较小,这种自旋极化的效应越显。 相似文献
11.
W. Y. Cui S. Z. Wu G. Jin X. Zhao Y. Q. Ma 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,59(1):47-54
We investigate the electron transmission through a structure of
serial mesoscopic metallic rings coupled to two external leads. A
set of analytical expressions based on the quantum waveguide
transport and the transfer matrix method are derived and used to
discuss the effects of geometric configurations on transmission
probabilities. It is found that in the contact ring case the
existence of an applied magnetic flux is necessary to create
transmission gaps, while in the non-contact ring case transmission
gaps always appear irrespective of whether there is an applied
magnetic flux or not. The transmissions for periodic rings with a
defect ring and periodic rings built by two sorts of rings are
also briefly studied. It is also found that the transmission
periodicity with wave vector must be ensured by the
commensurability of two characteristic lengths, i.e., of the half
perimeter of a ring and the connecting wire between two adjacent
rings. The special points of wave vector and magnetic flux which
give rise to the transmission resonance and antiresonance are
analyzed in detail. 相似文献
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We present quantum mechanical calculations of magnetoconductance of narrow quantum waveguides in the presence of inhomogeneous perpendicular magnetic field with the use of a model of two coupled tight-binding chains and the transfer-matrix method. The variation of the magnetoconductance with the magnetic flux φ threading one unit cell in the chains for different Fermi energies of the electrons is presented. The effect of magnetically defined ‘barriers’ on the conductance as a function of the Fermi energy is studied in detail for various samples with different magnetically structural configurations. The profile of the conductance depends on the magnitude and the relative direction of the magnetic field piercing the magnetic ‘barriers’. The behaviors of the conductance for the linear-variation and other modulation functions of the magnetic field in a finite region are shown. The abrupt change of the magnetic field in the interface between two adjacent regions causes striking oscillation structures imposed upon the conductance steps. When the magnetic field is varied smoothly (adiabatically) the oscillation structures in the conductance are substantially suppressed and smeared out and finally replaced by the rounded conductance step in the corner. The presence of a magnetically defined cavity in the waveguide leads to pronounced oscillations and the appearance of resonant dip-peak pair in the conductance. 相似文献
14.
M. P. Trushin A. L. Chudnovskiy 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,52(4):547-555
We have found a manifestation of spin-orbit Berry phase in the conductance
of a mesoscopic loop with Rashba spin-orbit coupling placed in an external magnetic field
perpendicular to the loop plane.
In detail, the transmission probabilities for a straight quantum wire
and for a quantum loop made of the same wire have been calculated and
compared with each other.
The difference between them has been investigated and identified with
a manifestation of spin-orbit Berry phase.
The non-adiabaticity effects at small radii of the loop have been found as well. 相似文献
15.
Danneau R Klochan O Clarke WR Ho LH Micolich AP Simmons MY Hamilton AR Pepper M Ritchie DA Zülicke U 《Physical review letters》2006,97(2):026403
We have studied the Zeeman splitting in ballistic hole quantum wires formed in a (311)A quantum well by surface gate confinement. Transport measurements clearly show lifting of the spin degeneracy and crossings of the subbands when an in-plane magnetic field B is applied parallel to the wire. When B is oriented perpendicular to the wire, no spin splitting is discernible up to B = 8.8 T. The observed large Zeeman splitting anisotropy in our hole quantum wires demonstrates the importance of quantum confinement for spin splitting in nanostructures with strong spin-orbit coupling. 相似文献
16.
Magnetic field induced exciton binding energy is investigated in a strained InAs/GaAs quantum wire within the framework of single band effective mass approximation. The strain contribution to the potential is determined through deformation potentials. The interband emission energy of strained InAs/GaAs wire is investigated in the influence of magnetic field with the various structural parameters. Magnetic field induced photoionization cross section of the exciton is studied. The total optical absorption and the refractive index changes as a function of normalized photon energy between the ground and the first excited state in the presence of magnetic field are analyzed. The optical absorption coefficients and the refractive index changes strongly depend on the incident optical intensity and the magnetic field. The occurred blueshift of the resonant peak due to the magnetic field will give the information about the variation of two energy levels in the quantum well wire. The optical absorption coefficients and the refractive index changes are strongly dependent on the incident optical intensity and the magnetic field. 相似文献
17.
《Physica E: Low-dimensional Systems and Nanostructures》2009,41(10):3155-3159
The spin transport of holes through a quantum wire made of many identical T-shaped diluted magnetic semiconductor/semiconductor units is investigated theoretically. The spin-down and spin-up transmission coefficients have been studied as a function of stub parameters. The spin-up transmission coefficient as a function of the stub length is extremely negligible, in the case of multiple-stub quantum wire, while the spin-down transmission coefficient shows a nearly periodic behaviour with regions of large transmission separated by forbidden bands. The spin polarization switches periodically between one and zero as the stub length is changed and shows a square-wave pattern. 相似文献
18.
The physical properties of magnetic domain walls and electrical conductivity of permalloy thin films under external magnetic fields were studied. Using a magnetic force microscope (MFM), we observed the variation of domain configurations with the change of applied magnetic field for different film thicknesses of 245, 320, and 415 nm. A superconducting quantum interference device (SQUID) was exploited to measure the magnetization loop for the applied magnetic field either parallel or perpendicular to the normal direction of the surface. We also found that the resistivity increases significantly as the electrical current conduction changed from parallel to perpendicular to the domain walls. 相似文献
19.
采用散射矩阵方法,研究了在应力自由和硬壁两种典型的边界条件下含半圆弧形腔的量子波导中声学声子输运和热导性质.结果表明在两种边界条件下声子透射谱和热导有着不同的特征.在应力自由边界条件下,能观察到普适的量子化热导现象,当结构为一理想的量子线时,在低温区域有一个量子化平台出现,而当半圆弧形结构存在时,非均匀横向宽度引发的弹性散射使得量子化平台被破坏;在硬壁边界条件下,不可能观察到量子化热导现象,热导随温度的增加单调上升;计算结果表明还可以通过调节半圆弧形结构的半径来调控声子的输运概率和热导.
关键词:
声学声子输运
热导
量子体系 相似文献
20.
Danneau R Klochan O Clarke WR Ho LH Micolich AP Simmons MY Hamilton AR Pepper M Ritchie DA 《Physical review letters》2008,100(1):016403
We study the anomalous conductance plateau around G=0.7(2e2/h) and the zero bias anomaly in ballistic hole quantum wires with respect to in-plane magnetic fields applied parallel B parallel and perpendicular B perpendicular to the quantum wire. As seen in electron quantum wires, the magnetic fields shift the 0.7 structure down to G=0.5(2e2/h) and simultaneously quench the zero bias anomaly. However, these effects are strongly dependent on the orientation of the magnetic field, owing to the highly anisotropic effective Landé g-factor g* in hole quantum wires. Our results highlight the fundamental role that spin plays in both the 0.7 structure and zero bias anomaly. 相似文献