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We theoretically investigate properties of the ground state of a closed dot-ring system with a magnetic flux in the Kondo regime by means of a tight-banding Anderson Hamiltonian, using the Slave-Boson mean-field approach. The persistent current shows interesting dependences on the parity and on the size of the system. The signature of Kondo resonance at ζk/L = 0.15 is expected to be observed experimentally in the future. With the intensity of the coupling tD changes from weak to strong, the properties of the system changes largely, which are different from the in-line one because of the attached dot. 相似文献
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我们利用单杂质Anderson模型及运动方程等理论,通过求解格林函数的方法研究了通过T型量子点结构(耦合于铁磁电极和介观环量子点结构)的自旋极化输运过程.研究结果表明,与量子点相耦合的铁磁电极中的极化强度是控制量子点电子输运的重要参数,由此可以达到自旋阀效应.另外我们还发现与量子点相耦合的介观环中的磁通会影响电子自旋向上和自旋向下近藤共振峰的分裂程度,但若加入适当的外磁场,那么这样的分裂将被抵消。 相似文献
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The properties of the ground state of a closed dot-ring system with a magnetic flux in the Kondo regime are studied theoretically by means of a one-impurity Anderson Hamiltonian. The Hamiltonian is solved by means of the slave-boson mean-field theory. It is shown that at T=0, a suppressed Kondo effect exists in this system even when the mean level spacing of electrons in the ring is larger than the bulk Kondo temperature. The physical quantities depend sensitively on both the parity of the system and the size of the ring; the rich physical behaviour can be attributed to the coexistence of both the finite-size effect and the Kondo screening effect. It is also possible to detect the Kondo screening cloud by measuring the persistent current or the zero field impurity susceptibility χ_{imp} directly in future experiments. 相似文献
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We theoretically study the properties of the ground state of a series-coupled double quantum dot embedded in a mesoscopic ring in the Kondo regime by means of the two-impurity Anderson Hamiltonian. The Hamiltonian is solved by means of the slave-boson mean-field theory. It is shown that two dots can be coupled coherently,which is reflected in the appearance of parity effects and the complex current-phase relation in this system. This system might be a possible candidate for future device applications. 相似文献
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Spin-Polarized Transport through the T-Shaped Double Quantum Dots with Fano-Kondo Interaction 下载免费PDF全文
We theoretically investigate the spin-polarized transport properties of the T-shaped double quantum dots coupled to two ferromagnetic leads by the Anderson Hamiltonian. The Hamiltonian is solved by means of the slave-boson mean-field theory. We calculate the density of states and the liner conductance in this system with both parallel and antiparallel lead-polarization alignments, and our results show that the transport properties of this system depend on both the tunnelling strength between the two dots and the spin-polarized strength p. This system is a possible candidate for spin valve transistors in the spintronics. 相似文献
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最近提出的一个构建相干态的方案中,需要精确求解一个时间相关的常微分方程.基于代数动力学理论,利用该方程具有的SU(1,1)动力学对称性,提出了对此方程在含时系数取任意函数形式时的统一的精确求解方法,并且得到了严格的解析解.运用这个精确解,就可以构造相应物理系统的精确相干态的具体表达式.给出了一个解例,即频率取"快变"函数的情形.利用得到的精确结果,讨论了这个系统的量子涨落(量子噪声)随时间演化的情况.针对动量算符不确定度随时间演化的曲线的性态,指出在制备这个系统压缩态时可以利用的一些性质.最后,讨论了这个量子系统的不确定关系随时间演化的情况. 相似文献
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We have investigated the persistent current in a mesoscopic ring with a side-coupled quantum dot. The problems are probed by using the one-impurity Anderson Hamiltonian and are treated with the slave boson mean field theory. It is shown that the persistent current in this system has the spin fluctuations, and the charge transfers between the two subsystems are suppressed in the limit of Δ/T_K^0《1. The minimum value of the persistent current for ξ_K/L=5 of the odd parity system provides an opportunity to detect the Kondo screening cloud. 相似文献