Coupling effects in artificial nano-dot lattices

新的集体电子态出现在简单金属或自旋掺杂金属纳米尺寸元素的有序阵列中，如果它们通过自旋携带电荷的隧穿耦合。正是这种耦合的强度与量子尺寸效应和阵列中无序的可能影响相结合，决定了这些集体态作为整个系综的新兴特性的特征。金属纳米点阵列中绝缘和导电基态之间的交叉性质是这方面的一个重要研究问题。理想情况下，这个问题应该在模型系统上研究，对于模型系统，纳米点的尺寸和它们的相互耦合强度可以很好地控制。在这个项目中，我们使用这样一个模型系统的基础上，铂纳米点阵列与精确可调的纳米点之间的隧道耦合来研究尺寸依赖的绝缘体到金属的交叉或相变的阵列。此外，我们奠定了基础，在不久的将来，这种方法的扩展到铜纳米点阵列与可变程度的铁杂质掺杂。在这样的阵列中，可以研究点间耦合和有限尺寸效应对近藤屏蔽云发展的影响。我们达到这些目标，通过应用和推进最近开发的聚焦电子束诱导沉积结合选择性区域原子层沉积的方法。我们的方法将在更广泛的介观物理学和强相关金属物理学领域的纳米结构制备更普遍的重要性。

New collective electronic states arise in ordered arrays of simple metallic or spin-doped metallic nanometer-sized elements, if they are coupled by tunneling of spin-carrying charges. It is the strength of this coupling in conjunction with possible influences of quantum-size effects and disorder in the arrays which governs the character of these collective states as emerging properties of the whole ensemble. The nature of the crossover between insulating and conducting ground states in metallic nano-dot arrays represents an important research questions in this regard. Ideally, this question should be studied on model systems for which the size of the nano-dots and their mutual coupling strength can be well controlled. In this project we use such a model system based on platinum nano-dot arrays with precisely tunable tunnel coupling between the nano-dots to study the dimensionality-dependent insulator-to-metal crossover or phase transition of the arrays. Furthermore, we lay the foundation for the extension of this approach in the near future to copper nano-dot arrays with variable degree of iron impurity doping. In such arrays the consequences of inter-dot coupling and finite size effects on the development of a Kondo screening cloud can be studied. We reach these objectives by applying and advancing recently developed methods of focused electron beam induced deposition combined with selective area atomic layer deposition. Our methodological approach will be of more general importance for nanostructure preparation in the wider fields of mesoscopic physics and the physics of strongly correlated metals.