By current pulses, the conductance of superconducting atomic contacts can be switched hysteretically between two well-defined values, making the contact act as an atomic-scale memory. The conductance change is realized by the change in position of individual atoms. The goal of this combined experimental and theoretical project is to understand electromigration at the atomic scale, to elucidate the functioning of the atomic memories and to explore their applicability in nanoelectronic circuits under various conditions. To this end, we will fabricate and investigate current-driven atomic switches made from several superconducting and non-superconducting metals to elucidate the role of superconductivity for the switching mechanism. Furthermore we will extend the measurements to higher temperatures up to room temperature. From the theoretical side we will apply and extend the microscopic theory of electromigration in atomic-size structures by calculating current-induced forces, aiming at simulations of current-induced atomic motion for realistic nanocontacts. By combining molecular dynamics simulations with electronic structure and transport studies in the non-equilibrium, current-biased situation, we will determine the required threshold current for current-induced atomic reconfigurations and the atomic structure in the two states of a switch for various metals.
DFG Programme
Research Grants
