Currently, much attention focuses on metallic, magnetic or semiconducting nanoparticles and their remarkable optical and electronic properties. By contrast, superconducting nanoparticles and their assembly into larger structures are largely unexplored. This Small Grant for Exploratory Research investigates the possibility to create a new generation of solids from carefully selected nanometer-size particles that are superconductors. It brings together innovative ideas from particle assembly and nanofabrication. The focus of this effort will be to explore means to tune the conductance of self-assembled nanoparticle arrays. The understanding gained from this research is likely to lead to the development of new materials for magnetic and electronic applications. At the same time, this project will immerse competent graduate students in interdisciplinary nanoscience research at the interface between physics and materials science.
The nature of the transition between the superconducting, metallic and insulating states of matter has remained one of the most intriguing puzzles in condensed matter physics. Ultrathin superconducting films for many years have been a workhorse for investigations of the insulator to superconductor transition. However, their local morphology is often difficult to ascertain and control. For a new approach to investigate this transition, this Small Grant for Exploratory Research brings together innovative ideas from colloid self-assembly and nanofabrication to produce highly-ordered nanoparticle arrays. In such arrays the conductance is determined by inter-particle tunneling through short organic molecules that coat each particle and set the inter-particle spacing. The focus of this effort is to explore means to tune the tunneling conductance. If this conductance can be driven into the vicinity of the quantum resistance it should be possible to cross from the insulating state not just into a metallic but also, for superconducting nanoparticles, into the globally superconducting state. The project will provide competent graduate students with skills across a broad range of nanofabrication techniques as well as electronic transport measurements.
