Formation of Single Cu Atomic Chain in Nitrogen Atmosphere

We study the conductance and geometry of the Cu atomic junction in the presence of N2, through combination of experimental measurement and theoretical calculation. A mechanically controllable break-junction measurement at low temperature reveals N2 molecules stabilize a Cu atomic junction, and reduce its conductance value. The length analysis about the Cu atomic junction indicates that it is elongated with the length of a few atoms, although it is not elongated without molecules. We investigate Cu atomic junction’s geometry by calculating the conductance and total energies of the several models by changing the separation between two Cu electrodes. Through combination of experimental and theoretical study, we show that the Cu linear atomic chain is formed with the support of N2 molecule, and N2 molecule attached on the Cu linear atomic chain. The formation of Cu linear atomic chain is explained that attached N2 molecules reduce the surface energy of the Cu atomic junction or N2 molecule directly supports the Cu–Cu bond.