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提出了含δ势垒的多臂量子环模型.研究发现总磁通为零时,持续电流随半导体环增大发生非周期性振荡,下臂因含δ势垒而获得最小的平均持续电流.AB磁通增强时,持续电流会发生周期性等幅振荡,并与电极的磁矩方向以及隧穿电子的自旋方向相关.两电极磁矩方向平行时,Rashba自旋轨道耦合具有改变持续电流相位和相位差的效应;两电极磁矩方向反平行时,Rashba自旋轨道耦合具有改变持续电流振幅的效应.各臂之间持续电流的不同与臂长和磁通分布的差异相关.在一定条件下,两种波函数所对应的持续电流是可分离的.
关键词:
多臂量子环
持续电流
δ势垒
Rashba自旋轨道耦合 相似文献
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提出了中臂弯曲的多臂量子环模型,且是上臂最短和下臂最长的不等臂量子环.研究发现:总磁通为零时,持续电流随半导体环增大发生非周期性振荡,并与电极的磁矩方向及隧穿电子的自旋方向相关,下臂因为最长而获得最小的平均持续电流.AB磁通增强时,持续电流会发生周期性振荡,各臂之间明显出现相互制约的现象.各臂持续电流之间的差异与臂长和磁通分布相关,Rashba自旋轨道耦合具有改变持续电流相位和相位差的效应.在一定条件下,两种波函数所对应的持续电流是可分离的.
关键词:
多臂量子环
持续电流
Rashba自旋轨道耦合 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
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在有关偶数正多边形量子环对称连接特殊情形的自旋输运特性的研究基础上,进一步探讨了任意正多边形量子环的自旋输运性质.不仅解析地求解了相关电子散射问题,而且得到了 Landauer-Buttiker 电导的普遍公式,并讨论了它的圆环极限和 Aharonov-Casher 相位问题.结合数值计算,研究了正多边形量子环的Landauer-Buttiker 电导随多边形边数、引线连接方式、自旋轨道耦合强度以及电子波矢的周期变化特性和零点分布规律.
关键词:
Rashba 自旋-轨道耦合
Aharonov-Casher 相位
量子网络
量子输运 相似文献
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We theoretically study the persistent currents flowing in a Rashba quantum ring subjected to the Rashba spin-orbit interaction. By introducing uniform or nonuniform magnetization into the ring, we find that a nonzero persistent charge current circulates in the ring, which stems from the original equilibrium spin current due to the Rashba spin-orbit interaction. Because of broken time reversal symmetry, the two oppositely flowing spin-up and spin-down charge currents of the equilibrium spin current are no longer equal, and so a net persistent charge current can flow in the system. It is also found that the persistent current can be modulated by the Fermi energy, the Rashba spin-orbit interaction strength and the magnetization in the ring. Moreover, the magnetization perpendicular to the ring plane can optimize the current. The persistent current flowing in the ring is a manifestation of the nonzero equilibrium spin current existing in the ring. 相似文献
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Transport polygonal properties in a multi-terminal regular quantum ring with Rashba spin-orbit coupling 下载免费PDF全文
<正>Transport properties in a multi-terminal regular polygonal quantum ring with Rashba spin-orbit coupling(SOC) are investigated analytically using quantum networks and the transport matrix method.The results show that conductances remain at exactly the same values when the output leads are located at axisymmetric positions.However,for the nonaxisymmetrical case,there is a phase difference between the upper and lower arm,which leads to zero conductances appearing periodically.An isotropy of the conductance is destroyed by the Rashba SOC effect in the axisymmetric case. In addition,the position of zero conductance is regulated with the strength of the Rashba SOC. 相似文献
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Spin current and its heat effect in a multichannel quantum wire with Rashba spin-orbit coupling 下载免费PDF全文
Using the perturbation method,we theoretically study the spin current and its heat effect in a multichannel quantum wire with Rashba spin-orbit coupling.The heat generated by the spin current is calculated.With the increase of the width of the quantum wire,the spin current and the heat generated both exhibit period oscillations with equal amplitudes.When the quantum-channel number is doubled,the oscillation periods of the spin current and of the heat generated both decrease by a factor of 2.For the spin current j s,xy,the amplitude increases with the decrease of the quantum channel;while the amplitude of the spin current j s,yx remains the same.Therefore we conclude that the effect of the quantum-channel number on the spin current j s,xy is greater than that on the spin current j s,yx.The strength of the Rashba spin-orbit coupling is tunable by the gate voltage,and the gate voltage can be varied experimentally,which implies a new method of detecting the spin current.In addition,we can control the amplitude and the oscillation period of the spin current by controlling the number of the quantum channels.All these characteristics of the spin current will be very important for detecting and controlling the spin current,and especially for designing new spintronic devices in the future. 相似文献
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The spin current in a parabolically confined semiconductor
heterojunction quantum wire with Dresselhaus spin--orbit coupling is
theoretically studied by using the perturbation method. The formulae
of the elements for linear and angular spin current densities are
derived by using the recent definition for spin current based on spin
continuity equation. It is found that the spin current in this
Dresselhaus spin--orbit coupling quantum wire is antisymmetrical,
which is different from that in Rashba model due to the difference in
symmetry between these two models. Some numerical examples for the
result are also demonstrated and discussed. 相似文献
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The effect of Rashba spin-orbit coupling (SOC) on electron transport in asymmetrically coupled regular polygonal quantum ring is investigated. In absence of SOC, two kinds of conductance zeros appear periodically. In presence of SOC, one kind of conductance zero can be lifted by the Rashba SOC, the others persist. 相似文献