Electrical properties of individual CoPt/Pt multilayer nanowires characterized by in situ SEM nanomanipulators.

Here we report for the first time accurate and comprehensive measurements of electrical properties of individual CoPt/Pt multilayer nanowires both with periodic and non-periodic layer structures. A remarkably high failure current density of 1.69 × 10(12) A m(-2) for the periodic MNW and a similar 1.76 × 10(12) A m(-2) for the non-homogeneous MNW has been measured. The resistance of both types of multilayer nanowire structures are well fitted by a series resistance model, determining the separate resistance contribution of the component layers and magnetic/nonmagnetic interfaces for a single multilayer nanowire. The field-dependent interface resistance of both samples is calculated, 13.2 Ω for periodic layer structures and 4.84 Ω for non-periodic layer structures. The clear physical picture of the resistance distribution within individual multilayer nanowires is then determined. The accurate electrical testing of magnetic multilayer nanowires provides basic and necessary electrical parameters for their usage as building blocks or interconnects in nanoelectronics and nanosensors.

Electrical nanowelding and bottom-up nano-construction together using nanoscale solder.

A new bottom-up nanowelding technique enabling the welding of complex 3D nanoarchitectures assembled from individual building blocks using nanovolumes of metal solder is reported in this work. The building blocks of gold nanowires, (Co72Pt28/Pt)n multilayer nanowires, and nanosolder Sn99Au1 alloy nanowires were successfully fabricated by a template technique. Individual metallic nanowires dispersed on Si/SiO2(100 nm) wafers were manipulated and assembled together. Conductive nanostructures were then welded together by the new electrical nanowelding technique using nanovolumes of similar or dissimilar nanosolder. At the weld sites, nanoscale volumes of a chosen metal are deposited using nanosolder of a sacrificial nanowire, which ensures that the nanoobjects to be bonded retain their structural integrity. The whole nanowelding process is clean, controllable and reliable, and ensures both mechanically strong and electrically conductive contacts. The quality check of nanoweld achieve a resistance as low as 20 omega by using Sn99Au1 alloy solder. This technique should provide a promising way to conquer the challenge of the integration obstacle for bottom-up nanotechnology.

Conductive nichrome probe tips: fabrication, characterization and application as nanotools.

Conductive nichrome probe tips have been developed as functionalized nanotools for nanoscale electrical testing and nanowelding. The apex size and shape of the ultra-sharp probes is controllable and reproducible. Structural and chemical characterization have been systematically carried out. The conductive quality of these tips has been demonstrated using them for nanoscale electrical testing and as a nanotool for nanowelding, indicating that they can easily form remarkable low resistance ohmic contacts. Nichrome tips should have a wide application as nanotools in nanotechnology, and be advantageous in competition with other scanning probe tips because of their unique combination of high resistance to oxidation, high hardness and relatively high resistivity.

Bottom-up nanoconstruction by the welding of individual metallic nanoobjects using nanoscale solder.

We report that individual metallic nanowires and nanoobjects can be assembled and welded together into complex nanostructures and conductive circuits by a new nanoscale electrical welding technique using nanovolumes of metal solder. At the weld sites, nanoscale volumes of a chosen metal are deposited using a sacrificial nanowire, which ensures that the nanoobjects to be bonded retain their structural integrity. We demonstrate by welding both similar and dissimilar materials that the use of nanoscale solder is clean, controllable, and reliable and ensures both mechanically strong and electrically conductive contacts. Nanoscale weld resistances of just 20Omega are achieved by using Sn solder. Precise engineering of nanowelds by this technique, including the chemical flexibility of the nanowire solder, and high spatial resolution of the nanowelding method, should result in research applications including fabrication of nanosensors and nanoelectronics constructed from a small number of nanoobjects, and repair of interconnects and failed nanoscale electronics.