共查询到16条相似文献,搜索用时 375 毫秒
1.
2.
3.
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
4.
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
5.
采用一维量子波导理论研究了带有一个Stub的三臂环中的透射系数和持续电流.探讨了透射系数和持续电流对环的尺寸和Stub长度的依赖关系.结果发现:当k_1取某一个固定值,满足kL=nπ时,系统出现反共振现象.而且适当地调节系统的参数,可以出现明显的Fano共振现象. 相似文献
6.
7.
8.
9.
使用单杂质的Ansderson模型, 从理论上研究了一个嵌入单量子点Aharonov-Bohm环系统处在 近藤区时的基态性质, 并用slave-boson平均场方法求解了该模型.结果表明:在零温, 当介 观环内电子平均能级间隔大于近藤关联能时, 系统内仍然存在一个被减弱了的近藤效应;系 统的基态性质依赖于系统的宇称和环的大小;而尺寸效应和近藤屏蔽效应的共存导致了系统 丰富的物理性质.同时, 可以通过测量介观环中的持续电流和杂质磁化率, 达到探测近藤屏 蔽云的目的.
关键词:
持续电流
杂质磁化率
宇称效应
近藤效应
近藤屏蔽云 相似文献
10.
采用量子波导理论,研究了含杂质的介观结构中电子的透射几率和持续电流。结果表明:电子的透射几率及持续电流均随磁通量的变化作周期性振荡,周期大小是1;无论是否存在杂质,反共振(T=0)均出现在f=0.5的位置(当0≤f<1)。当两电子库间电流发生反转时,双Aharonov-Bohm环各环中的持续电流的大小均发生明显改变。 相似文献
11.
12.
The possibility of observing persistent voltage in superconducting rings of different arm widths is experimentally investigated. It was previously found that switching of the arms between superconducting and normal states by an AC current induces DC voltage oscillation in the magnetic field with a period corresponding to the flux quantum inside the ring. We used systems with a large number of asymmetric rings connected in series to investigate the possibility of observing this quantum phenomenon near the superconducting transition, where thermal fluctuations lead to switching of ring segments without an external influence and the persistent current is much smaller than in the superconducting state. 相似文献
13.
We investigate the equilibrium property of a mesoscopic ring with a spin-orbit interaction. It is well known that, for a normal mesoscopic ring threaded by a magnetic flux, the electron acquires a Berry phase that induces the persistent (charge) current. Similarly, the spin of an electron acquires a spin Berry phase traversing a ring with a spin-orbit interaction. It is this spin Berry phase that induces a persistent spin current. To demonstrate its existence, we calculate the persistent spin current without an accompanying charge current in the normal region in a hybrid mesoscopic ring. We point out that this persistent spin current describes the real spin motion and can be observed experimentally. 相似文献
14.
15.
In normal mesoscopic metals of a ring topology persistent currents can be induced by threading the center of the ring with
a magnetic flux. This phenomenon is an example of the famous Aharonov-Bohm effect. In the paper we study the current vs the external constant magnetic flux characteristics of the system driven by both the classical and the quantum thermal fluctuations.
The problem is formulated in terms of Langevin equations in classical and quantum Smoluchowski regimes. We analyze the impact
of the quantum thermal fluctuations on the current-flux characteristics. We demonstrate that the current response can be changed
from paramagnetic to diamagnetic when the quantum nature of the thermal fluctuations increases. 相似文献
16.
A.J. Fendrik M.J. Sánchez 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,14(4):725-732
In the present article we perform analytical and numerical calculations related to persistent currents in 2D isolated mesoscopic
annular cavities threaded by a magnetic flux. The system considered has a high number of open channels and therefore the single
particle spectrum exhibits many level crossings as the flux varies. We determine the effect of the distribution of level crossings
on the typical persistent current.
Received 5 July 1999 相似文献