Coupling effects in artificial nano-dot lattices

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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.