Shuttle transport in nanostructures

Book chapter, 2006

The coupling between mechanical deformations and electronic charge transport in nanostructures and in composite materials with nanoscale components gives rise to a new class of phenomena | nanoelectromechanical transport | and opens up a new route in nanotechnology. The interplay between the electronic and mechanical degrees of freedom is especially important in nanocomposites consisting of materials with very di®erent elastic properties. Mechanical degrees of freedom take on a primary role in the charge transfer process in many single-electron devices, where transport is controlled by quantum-mechanical tunnelling and Coulomb interactions, but where tunnel barriers can be modi¯ed as a result of mechanical motion. A typical system of this kind is a single-electron transistor (SET) with deformable tunnel barriers, a so called Nano-Electro-Mechanical SET (NEM- SET). The new kind of electron transport in this and other types of nanodevices is referred to as "shuttle transport" of electrons, which implies that electrons is transferred between metallic leads via a movable small-sized cluster. The present review is devoted to the fundamental aspects of shuttle transport and to a description of major developments in the theoretical and experimental research in the ¯eld. Prospective applications of this exciting phenomenon that remarkably combines traditional mechanics of materials with the most advanced e®ects of quantum physics, will also be touched upon.