Lateral and Temporal Dependence of the Transport through an Atomic Gold Contact under Light Irradiation: Signature of Propagating Surface Plasmon Polaritons

Abstract

Metallic point contacts (MPCs) with dimensions comparable to the Fermi wavelength of conduction electrons act as electronic waveguides and might operate as plasmon transmitters. Here we present a correlated study of optical and conductance response of MPCs under irradiation with laser light. For elucidating the role of surface plasmon polaritons (SPPs), we integrate line gratings into the leads that increase the SPP excitation efficiency. By analyzing spatial, polarization, and time dependence, we identify two SPP contributions that we attribute to transmitted and decaying SPPs, respectively. The results demonstrate the role of SPPs for optically controlling the transport in metallic nanostructures and are important for designing opto-nanoelectronic devices.

Time-resolved optical measurement of thermal transport by surface plasmon polaritons in thin metal stripes

“…The light polarization could be chosen perpendicular or parallel to the long axis of the stripe (i.e., parallel or perpendicular to the lines of the grating), allowing for a strongly suppressed or an efficient generation of SPPs, respectively. 16,24 For comparison, we illuminated in some of the experiments an unstructured part of the gold stripe with the focused light of a 405 nm laser diode. At this wavelength, gold absorbs a major part of the incident light and the laser beam can be considered as a simple local heat source.An example for this latter case of pure heating is presented in Fig.…”

“…14,15 In this context, localized surface plasmons as well as running surface plasmon polaritons (SPPs) [16][17][18][19] might have a major impact for the interpretation of nano-optoelectronic experiments. [20][21][22][23][24] A prerequisite for assessing these nanoscale effects is the understanding of heat transport by plasmons in mesoscopic systems, where a local equilibrium between the electronic and the phononic system can safely be assumed and, thus, a local temperature is well-defined. In metallic nanoparticles, localized plasmons can lead to hot spots with very high field intensities, leading, e.g., to local photopolymerization of surrounding resist and even to local melting of the nanostructures.…”

Plasmonic Nanogaps: From Fabrications to Optical Applications

“…Another method to form nanoscale gaps is the mechanically controllable break junction (MCBJ) technique, which has been used for decades to form molecular junctions; a schematic drawing of the sample mounting of the MCBJ technique is presented in Figure . Its principle is as follows: a metallic wire is positioned on top of an elastic substrate, which serves as the bending beam.…”

“…In the optimized MCBJ route, which was named as electrochemically assisted MCBJ (ECMCBJ), fabrication of adjustable nanogap only requires two economic and simple fabrication techniques: photolithography and electrochemical deposition, instead of the expensive and time consuming electron beam lithography. Benner et al used the MCBJ technique to fabricate metallic point contacts (MPCs) of gold at ambient conditions . By linking the optical and the transport results they elucidated that the contribution of surface plasmon polaritons (SPPs) to the conductance change.…”

Plasmon transmission through excitonic subwavelength gaps

“…We note that some issues related to this study were addressed in previous works. On the experimental side, Benner et al [84,85] have studied plasmon transmission (and electronic conduction) across small constrictions between metal wires, highlighting the need to account for heating and thermal expansion effects in realistic experiments. Neuhauser and coworkers [68,69] have placed a single molecule between two metal spheres in order to simulate its effect on the plasmon-plasmon coupling.…”