Atomic Configuration and Conductance of Tantalum Single-Atom Contacts and Single-Atom Wires

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

“…The conductance of pure metal SAWWs depends on the wire length, atomic position, i.e., wire shape, and interatomic distance. ,,− ,, When impurity atoms of light elements are incorporated into pure metal SAWWs, the conductance decreases but never increases. ,,, In contrast, as shown in this study, the conductance of PtIr SAWWs changed in complexity for different element allocation. From the present results, we expect that a variety of conductance control is possible in alloy SAWWs via the element allocation even when the atomic configuration is fixed.…”

“…In nanometer-sized structures, SAWWs, which are one-dimensional single-atom arrays, are the finest solid structures and exhibit peculiar properties different from bulk and isolated single atoms. ,− Such ultimate structures emerge during thinning of nanometer-sized contacts before mechanical breaking . The conduction features of SAWWs, e.g., ballistic conduction and its opposite Peiels transition, have been found in studies based on scanning tunneling microscopy, mechanical controllable break junction techniques, and in situ transmission electron microscopy (TEM) employing mechanical breaking operation systems of nanometer-sized contacts. ,,,, Theoretical and calculation studies reveal that such conduction features are closely related to inherent SAWW structures. − In the mechanical breaking methods, in situ TEM enables the direct observation of the atomic configuration of SAWWs in addition to conductance. ,,,,− Thus, this method has been applied to SAWWs comprised of various single elements and the relationships between the length, atomic configuration, i.e., the shapes and interatomic distances, and the conductance have been investigated. For SAWWs comprised of several elements, i.e., alloy SAWWs, their stable structures and properties also depend on the allocation of elements. − However, when TEM is applied to alloy SAWWs, the identification of elements has been limited to elements having sufficiently different atomic numbers .…”

“…The conductance of pure metal SAWWs depends on the wire length, atomic position, i.e., wire shape, and interatomic distance. 11,12,[19][20][21][22][23][24]27,32 When impurity atoms of light elements are incorporated into pure metal SAWWs, the conductance decreases but never increases. 19,22,24,28 In contrast, as shown in this study, the conductance of PtIr SAWWs changed in complexity for different element allocation.…”

Surface reconstruction in gold nanowires

“…The atomic configuration on crystal surfaces is modulated and unit structures different from ideal surfaces appear, as exemplified by the dimer-adatom-stacking fault model of silicon surface reconstruction 1 . Peculiar atomic configurations also emerge in nanometer-sized isolated structures, such as nanoclusters, nanowires (NWs) and nanotubes 1 , 2 : five-fold symmetric multiply twinned nanoclusters having a disclination 3 , 4 , nanotubes with helical structures 5 , gold (Au) NWs comprising a body-centered tetragonal structure 6 , amorphized pure metal nanocontacts (NCs) 7 , 8 , and atomic chains in which single atoms align on a line 9 – 12 . In addition to increased surface area-to-interior volume ratio effects 2 , 13 , such peculiar atomic configurations of surfaces and nanostructures lead to new non-bulky inherent properties, inspiring the creation of devices with unprecedented electrical, mechanical, optical, and magnetic functions 14 – 16 .…”

“…The specific nanostructures can be roughly classified into two types: those where the entire crystal structure changes such as NWs and nanotubes having helical structures and amorphized NCs 5 , 6 , 8 , 12 ; and those where twins and specific crystal boundaries are introduced in nanostructures, such as multiply twinned nanoclusters 3 , 4 . In this study, we demonstrate a new type of nanostructure belonging to neither of these two types, i.e., the formation of NWs for which monatomic surface layers are stabilized via reconstruction by a stress-applied electromigration method.…”