Formation of pentagonal Cu nano wires

The development of nano/molecular devices will require atomic-sized electrical contacts or nano metric conductors for wiring. As metal nano wires exhibit quantized conductance at room temperature, quantum transport effects will play an important role int he practical implementation of nano devices. As copper is currently used as interconnecting metal in standard microelectronics, the characterization of Cu nano wire properties deserves special attention. In this work, we show a detailed study of structural and electronic properties of atomic-sized Cu wires. In particular, we have established a complete correlation between the conductance and the structure by associating real-time atomic resolution transmission electron microscopy imaging with molecular dynamic simulations, conductance measurements and conductance calculations. Our study has revealed the structural relaxation of Cu wires forming a pentagonal atomic arrangement along the [110] direction that allows a electronic transport of ∼4.5 conductance quanta. (author)