Vertically coupled double quantum dots in magnetic fields
Vertically coupled double quantum dots in magnetic fields
复制标题
磁场中垂直耦合双量子点
DOI：
10.1103/physrevb.59.5817
复制
发表时间：
1999
影响因子：
3.7
通讯作者：
H. Aoki
中科院分区：
文献类型：
--
作者：
H. Imamura;P. Maksym;H. Aoki
利用精确对角化方法研究了垂直耦合双量子点的基态和激发态性质。幻数的总角动量，最小化的总能量被发现，以反映由层内相关为主的电子配置和层间相关为主的交叉。交叉的位置由层间电子隧穿和磁场的强度决定。幻数应该对远红外光吸收光谱有可观察到的影响，因为当两个点的限制势不同时，Kohn定理[Phys. Rev. 123，1242（1961）]不成立。这确实是证实了这里从数值计算，包括朗道级混合。我们的结果充分考虑了自旋自由度的影响。一个关键的特征是，由于强的电子关联，系统的总自旋S和魔数角动量密切相关。因此，当磁场变化时，S与总角动量一起跳跃。一个重要的结果是，由于自旋选择规则，自旋阻塞（单电子隧穿的抑制）应该发生在某些磁场区域。由于层内和层间相关性的存在所产生的灵活性，在双点中比在单点中更容易实现自旋阻断。
Ground- and excited-state properties of vertically coupled double quantum dots are studied by exact diagonalization. Magic-number total angular momenta that minimize the total energy are found to reflect a crossover between electron configurations dominated by intralayer correlation and those dominated by interlayer correlation. The position of the crossover is governed by the strength of the interlayer electron tunneling and magnetic field. The magic numbers should have an observable effect on the far-infrared optical-absorption spectrum, since Kohn's theorem [Phys. Rev. 123, 1242 (1961)] does not hold when the confinement potential is different for two dots. This is indeed confirmed here from a numerical calculation that includes Landau-level mixing. Our results take full account of the effect of spin degrees of freedom. A key feature is that the total spin S of the system and the magic-number angular momentum are intimately linked because of strong electron correlation. Thus S jumps hand in hand with the total angular momentum as the magnetic field is varied. One important consequence of this is that the spin blockade (an inhibition of single-electron tunneling) should occur in some magnetic field regions because of a spin selection rule. Owing to the flexibility arising from the presence of both intralayer and interlayer correlations, the spin blockade is easier to realize in double dots than in single dots.