Element Mapping in Single-Atom-Width Platinum-Iridium Wires

Single-atom-width wires (SAWWs) of platinum-iridium (PtIr) alloy were produced by mechanical breaking inside a transmission electron microscope. The formation dynamics, the atomic configuration, and the conductance were observed in situ. From the observed lattice images of the SAWWs and image simulation, the structure models, i.e., the configurations of atom position and element allocation, were constructed. Using the experiment-based structural models, the first-principle calculation of the conductance was performed. The atomic configuration and element allocation of the observed SAWWs were identified via the combination of the lattice imaging and calculation. The conductance of PtIr SAWWs changed in complexity for different element allocation in addition to the wire length and the configuration of the constituent atoms, which was difficult to presage from the conductance features of pure metal SAWWs. The present study revealed that the conductance of alloy SAWWs can be controlled by element allocation.