School of Physics, University College Dublin, Dublin 4, Ireland.
Institute for Theoretical Physics, Utrecht University, Princetonplein 5, Utrecht 3584 CE, The Netherlands.
Nat Commun. 2017 May 11;8:15210. doi: 10.1038/ncomms15210.
Molecular electronics offers unique scientific and technological possibilities, resulting from both the nanometre scale of the devices and their reproducible chemical complexity. Two fundamental yet different effects, with no classical analogue, have been demonstrated experimentally in single-molecule junctions: quantum interference due to competing electron transport pathways, and the Kondo effect due to entanglement from strong electronic interactions. Here we unify these phenomena, showing that transport through a spin-degenerate molecule can be either enhanced or blocked by Kondo correlations, depending on molecular structure, contacting geometry and applied gate voltages. An exact framework is developed, in terms of which the quantum interference properties of interacting molecular junctions can be systematically studied and understood. We prove that an exact Kondo-mediated conductance node results from destructive interference in exchange-cotunneling. Nonstandard temperature dependences and gate-tunable conductance peaks/nodes are demonstrated for prototypical molecular junctions, illustrating the intricate interplay of quantum effects beyond the single-orbital paradigm.
分子电子学提供了独特的科学和技术可能性，这源于器件的纳米尺度和其可重复的化学复杂性。在单分子结中已经实验证明了两种基本但不同的效应，它们没有经典的类似物：由于竞争电子输运途径而产生的量子干涉，以及由于强电子相互作用引起的纠缠而产生的近藤效应。在这里，我们统一了这些现象，表明通过自旋简并分子的输运可以通过近藤相关被增强或阻断，这取决于分子结构、接触几何形状和施加的栅极电压。我们开发了一个精确的框架，根据该框架可以系统地研究和理解相互作用的分子结的量子干涉特性。我们证明，一个精确的近藤介导的电导节点是由交换穿隧中的相消干涉产生的。对于典型的分子结，我们演示了非标准的温度依赖性和栅极可调的电导峰/节点，说明了超越单轨道范例的量子效应的复杂相互作用。
