190 research outputs found
Parallel, Series, and Intermediate Interconnections of Optical Nanocircuit Elements Part 1: Analytical Solution
Following our recent development of the paradigm for extending the classic
concepts of circuit elements to the infrared and optical frequencies [N.
Engheta, A. Salandrino, A. Alu, Phys. Rev. Lett. 95, 095504 (2005)], in this
paper we investigate the possibility of connecting nanoparticles in series and
in parallel configurations, acting as nanocircuit elements, In particular, we
analyze a pair of conjoined half-cylinders, whose relatively simple geometry
may be studied and analyzed analytically. In this first part of the work, we
derive a closed-form quasi-static analytical solution of the boundary-value
problem associated with this geometry, which will be applied in Part II for a
nanocircuit and physical interpretation of these results.Comment: 21 pages, 5 figure
AFM manipulation of gold nanowires to build electrical circuits
This document is the Accepted Manuscript version of a Published Work that appeared in final form in Nano Letters , copyright © American Chemical Society after peer review and technical editing by the publisher. To acces final work see âAFM Manipulation of Gold Nanowires To Build Electrical Circuitsâ, Nano Letters 19.8 (2019): 5459-5468, https://doi.org/10.1021/acs.nanolett.9b01972We introduce scanning-probe-assisted nanowire circuitry (SPANC) as a new method to fabricate electrodes for the characterization of electrical transport properties at the nanoscale. SPANC uses an atomic force microscope (AFM) to manipulate nanowires to create complex and highly conductive nanostructures (paths) that work as nanoelectrodes, allowing connectivity and electrical characterization of other nano-objects. The paths are formed by the spontaneous cold welding of gold nanowires upon mechanical contact, leading to an excellent contact resistance of âŒ9 Ï/junction. SPANC is an easy to use and cost-effective technique that fabricates clean nanodevices. Hence, this new method can complement and/or be an alternative to other well-established methods to fabricate nanocircuits such as electron beam lithography (EBL). The circuits made by SPANC are easily reconfigurable, and their fabrication does not require the use of polymers and chemicals. In this work, we present a few examples that illustrate the capabilities of this method, allowing robust device fabrication and electrical characterization of several nano-objects with sizes down to âŒ10 nm, well below the current smallest size able to be contacted in a device using the standard available technology (âŒ30 nm). Importantly, we also provide the first experimental determination of the sheet resistance of thin antimonene flake
A comparative study of semiconductor-based plasmonic metamaterials
Recent metamaterial (MM) research faces several problems when using
metal-based plasmonic components as building blocks for MMs. The use of
conventional metals for MMs is limited by several factors: metals such as gold
and silver have high losses in the visible and near-infrared (NIR) ranges and
very large negative real permittivity values, and in addition, their optical
properties cannot be tuned. These issues that put severe constraints on the
device applications of MMs could be overcome if semiconductors are used as
plasmonic materials instead of metals. Heavily doped, wide bandgap oxide
semiconductors could exhibit both a small negative real permittivity and
relatively small losses in the NIR. Heavily doped oxides of zinc and indium
were already reported to be good, low loss alternatives to metals in the NIR
range. Here, we consider these transparent conducting oxides (TCOs) as
alternative plasmonic materials for many specific applications ranging from
surface-plasmon-polariton waveguides to MMs with hyperbolic dispersion and
epsilon-near-zero (ENZ) materials. We show that TCOs outperform conventional
metals for ENZ and other MM-applications in the NIR.Comment: 16 pages, 7 figure
Breaking the challenge of signal integrity using time-domain spoof surface plasmon polaritons
In modern integrated circuits and wireless communication systems/devices,
three key features need to be solved simultaneously to reach higher performance
and more compact size: signal integrity, interference suppression, and
miniaturization. However, the above-mentioned requests are almost contradictory
using the traditional techniques. To overcome this challenge, here we propose
time-domain spoof surface plasmon polaritons (SPPs) as the carrier of signals.
By designing a special plasmonic waveguide constructed by printing two narrow
corrugated metallic strips on the top and bottom surfaces of a dielectric
substrate with mirror symmetry, we show that spoof SPPs are supported from very
low frequency to the cutoff frequency with strong subwavelength effects, which
can be converted to the time-domain SPPs. When two such plasmonic waveguides
are tightly packed with deep-subwavelength separation, which commonly happens
in the integrated circuits and wireless communications due to limited space, we
demonstrate theoretically and experimentally that SPP signals on such two
plasmonic waveguides have better propagation performance and much less mutual
coupling than the conventional signals on two traditional microstrip lines with
the same size and separation. Hence the proposed method can achieve significant
interference suppression in very compact space, providing a potential solution
to break the challenge of signal integrity
The Role of Alternance Symmetry in Magnetoconductance
We show that the direction of coherent electron transport across a cyclic
system of quantum dots or a cyclic molecule can be modulated by an external
magnetic field if the cycle has an odd number of hopping sites, but the
transport becomes completely symmetric if the number is even. These contrasting
behaviors, which remain in the case of interacting electrons, are a consequence
of the absence or presence of alternance symmetry in the system. These findings
are relevant for the design of nanocircuits based on coupled quantum dots or
molecular junctions.Comment: to be published in PR
Detection of Tiny Mechanical Motion by Means of the Ratchet Effect
We propose a position detection scheme for a nanoelectromechanical resonator
based on the ratchet effect. This scheme has an advantage of being a dc
measurement. We consider a three-junction SQUID where a part of the
superconducting loop can perform mechanical motion. The response of the ratchet
to a dc current is sensitive to the position of the resonator and the effect
can be further enhanced by biasing the SQUID with an ac current. We discuss the
feasibility of the proposed scheme in existing experimental setups.Comment: 8 pages, 9 figure
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