In this article, we present a comprehensive investigation of the photothermal properties of plasmonic nanowire networks. We measure the local steady-state temperature increase, heat source density, and absorption in Ag, Au, and Ni metallic nanowire networks under optical illumination. This allows direct experimental confirmation of increased heat generation at the junction between two metallic nanowires and stacking-dependent absorption of polarized light. Due to thermal collective effects, the local temperature distribution in a network is shown to be completely delocalized on a micrometer scale, despite the nanoscale features in the heat source density. Comparison of the experimental temperature profile with numerical simulation allows an upper limit for the effective thermal conductivity of a Ag nanowire network to be established at 43 Wm(-1) K(-1) (0.1 κbulk).

Crystalline aluminum oxide is a brittle ceramic material. Here we show that individual alumina nanotubes with internal and external radii of ∼15 nm and ∼50 nm, respectively and lengths of the order of 100 μm can be readily separated from amorphous alumina membranes fabricated by a hard anodisation process under a magnetic field of up to 1.5 T. The ceramic nanotubes are extremely flexible and exhibit an exceptional plasticity of ±70% at room temperature without breaking. Elastic properties investigated by the double clamped beam method include a tensile strength of 4.1 GPa, corresponding to a breaking strain of 5%. These values are respectively 17 and 70 times greater than those of polycrystalline alumina fibres. The plasticity of anodic amorphous alumina helps explain the formation of ordered arrays of nanopores in the alumina membranes.

We present the preparation and measurements of nanowires of single-crystal NbSe2. These nanowires were prepared on ultrathin ( 10 nm) flakes of NbSe2 mechanically exfoliated from a bulk single crystal using a process combining electron beam lithography and reactive plasma etching. The electrical contacts to the nanowires were prepared using Ti/Au. Our technique, which overcomes several limitations of methods developed previously for fabricating superconducting nanowires, also allows for the preparation of complex superconducting nanostructures with a desired geometry. Current-voltage characteristics of individual superconducting single-crystal nanowires with widths down to 30 nm and cross-sectional areas as low as 270 nm 2 were measured for the first time.Nanoscale superconductors (wires, disks, loops, etc.) have long been a system of fundamental interest. Investigation of phase slips induced by either thermal activation (TAPS)1-6 or macroscopic quantum tunneling (MQT) 6-10 in superconducting nanowires has deepened our understanding of phase coherence at a macroscopic length scale. Work on doubly-connected superconductors, such as ultrathin hollow cylinders of superconductors prepared on an insulating cylindrical substrate -which were shown to exhibit both a destructive regime near half-integer flux quanta, 11-13 as predicted originally by de Gennes, 14 and a quantum phase transition near the onset of the destructive regime 12 -has shown that sample topology plays an important role in determining the properties of nanoscale superconductors. The destructive regime is the Little-Parks effect 15 in the limit of an ultrasmall cylinder diameter. Furthermore, planar doubly-connected superconducting nanostructures exhibit a Little-Parks-de Gennes effect in which the destructive regime is manipulated through sample geometry by adding a side branch to a superconducting nanoloop.

Numerical calculations on a mesoscopic ring of a type II superconductor in the London limit suggest that an Abrikosov vortex can be trapped in such a structure above a critical magnetic field and generate a phase shift in the magnetoresistance oscillations. We prepared submicron-sized superconducting loops of single-crystal, type II superconductor NbSe2 and measured magnetoresistance oscillations resulting from vortices crossing the loops. The free energy barrier for vortex crossing determines the crossing rate and is periodically modulated by the external magnetic flux threading the loop. We demonstrated experimentally that the crossing of vortices can be directed at a pair of constrictions in the loop, leading to more pronounced magnetoresistance oscillations than those in a uniform ring. The vortex trapping in both a simple ring and a ring featuring two constrictions was found to result in a phase shift in the magnetoresistance oscillations as predicted in the numerical calculations. The controlled crossing and trapping of vortices demonstrated in our NbSe2 devices provide a starting point for the manipulation of individual Abrikosov vortices, which is useful for future technologies.