Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Kraków, Poland.
J Phys Condens Matter. 2010 Nov 24;22(46):465801. doi: 10.1088/0953-8984/22/46/465801. Epub 2010 Nov 4.
We study the current flow through semiconductor quantum rings. In high magnetic fields the current is usually injected into the arm of the ring preferred by classical magnetic forces. However, for narrow magnetic field intervals that appear periodically on the magnetic field scale the current is injected into the other arm of the ring. We indicate that the appearance of the anomalous-non-classical-current circulation results from Fano interference involving localized resonant states. The identification of the Fano interference is based on the comparison of the solution of the scattering problem with the results of the stabilization method. The latter employs the bound-state type calculations and allows us to extract both the energy of metastable states localized within the ring and the width of resonances by analysis of the energy spectrum of a finite size system as a function of its length. The Fano resonances involving states of anomalous current circulation become extremely narrow on both the magnetic field and energy scales. This is consistent with the orientation of the Lorentz force that tends to keep the electron within the ring and thus increases the lifetime of the electron localization within the ring. Absence of periodic Fano resonances in electron transfer probability through a quantum ring containing an elastic scatterer is also explained.
我们研究了半导体量子环中的电流。在强磁场中，电流通常注入到经典磁力优先进入的环臂中。然而，对于磁场尺度上周期性出现的狭窄磁场区间，电流会注入到环的另一臂中。我们指出，反常非经典电流循环的出现是由于涉及局域共振态的 Fano 干涉。Fano 干涉的识别是基于散射问题的解与稳定化方法结果的比较。后者采用束缚态类型的计算，并允许我们通过分析有限大小系统的能谱作为其长度的函数，提取局域在环内的亚稳态的能量和共振的宽度。涉及反常电流循环的 Fano 共振在磁场和能量尺度上都变得非常狭窄。这与洛伦兹力的方向一致，洛伦兹力倾向于使电子保持在环内，从而增加了电子在环内局域的寿命。含有弹性散射体的量子环中电子转移概率没有周期性 Fano 共振也得到了解释。
