The key aim of the project is to correlate the electronic transport properties of nanoscale metallic contacts with their structure. The electronic transport properties through a metallic contact of atomic dimensions are governed by the atomic structure and by the chemical properties of the contact as well as by the wave nature of electrons. This leads to plateaus of the conductance measured as a function of contact size that do not necessarily correspond to integer multiples of the conductance quantum. I will investigate whether and how atomic as well as electronic shell effects influence the atomic structure of nanoscale metallic contacts. We will measure both electronic transport properties and structural properties concurrently and determine their mutual relation on each individual contact. The contacts will be fabricated by Joule heating a nanowire until thermally assisted electromigration sets in and thins the nanowire to form a contact. The structural properties of these nanocontacts will be studied using scanning force microscopy and scanning tunneling microscopy with atomic resolution in ultrahigh-vacuum. This approach will allow us to use clean superconducting contacts and to exploit superconductivity in order to study the electronic transport properties of the contacts. The electronic transport properties will be studied employing multiple Andreev reflections to determine the number and transmission coefficient of electronic conduction channels. Eventually, a deeper understanding of the relation between structure and electronic transport properties will be obtained which is a prerequisite to tailor the electronic transport properties of nanoscale metallic contacts.
Start Date: 01.01.2010 End Date: 31.12.2014 EU Contribution: 1.51 Mio. Euro Total Costs: 1.51 Mio. Euro Funding Scheme: ERC Starting Grant 2009