Gruss Daniel, Velizhanin Kirill A, Zwolak Michael
Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
Maryland Nanocenter, University of Maryland, College Park, MD 20742, USA.
Sci Rep. 2016 Apr 20;6:24514. doi: 10.1038/srep24514.
Landauer's formula is the standard theoretical tool to examine ballistic transport in nano- and meso-scale junctions, but it necessitates that any variation of the junction with time must be slow compared to characteristic times of the system, e.g., the relaxation time of local excitations. Transport through structurally dynamic junctions is, however, increasingly of interest for sensing, harnessing fluctuations, and real-time control. Here, we calculate the steady-state current when relaxation of electrons in the reservoirs is present and demonstrate that it gives rise to three regimes of behavior: weak relaxation gives a contact-limited current; strong relaxation localizes electrons, distorting their natural dynamics and reducing the current; and in an intermediate regime the Landauer view of the system only is recovered. We also demonstrate that a simple equation of motion emerges, which is suitable for efficiently simulating time-dependent transport.
兰道尔公式是研究纳米和介观尺度结中弹道输运的标准理论工具，但它要求结随时间的任何变化必须比系统的特征时间慢，例如局部激发的弛豫时间。然而，通过结构动态结的输运对于传感、利用涨落和实时控制越来越受到关注。在这里，我们计算了存在储层中电子弛豫时的稳态电流，并证明它会导致三种行为模式：弱弛豫给出接触限制电流；强弛豫使电子局域化，扭曲它们的自然动力学并降低电流；在中间模式下，仅恢复系统的兰道尔观点。我们还证明出现了一个简单的运动方程，它适用于有效地模拟随时间变化的输运。
