Tag Archives: information technology

A deep look at atomic switches

A July 19, 2019 news item on phys.org describes research that may result in a substantive change for information technology,

A team of researchers from Tokyo Institute of Technology has gained unprecedented insight into the inner workings of an atomic switch. By investigating the composition of the tiny metal ‘bridge’ that forms inside the switch, their findings may spur the design of atomic switches with improved performance.

A July 22, 2019 Tokyo Institute of Technology press release (also on EurekAlert but published July 19, 2019), which originated the news item, explains how this research could have such an important impact,

Atomic switches are hailed as the tiniest of electrochemical switches that could change the face of information technology. Due to their nanoscale dimensions and low power consumption, they hold promise for integration into next-generation circuits that could drive the development of artificial intelligence (AI) and Internet of Things (IoT) devices.

Although various designs have emerged, one intriguing question concerns the nature of the metallic filament, or bridge, that is key to the operation of the switch. The bridge forms inside a metal sulfide layer sandwiched between two electrodes [see figure below], and is controlled by applying a voltage that induces an electrochemical reaction. The formation and annihilation of this bridge determines whether the switch is on or off.

Now, a research group including Akira Aiba and Manabu Kiguchi and colleagues at Tokyo Institute of Technology’s Department of Chemistry has found a useful way to examine precisely what the bridge is composed of.

By cooling the atomic switch enough so as to be able to investigate the bridge using a low-temperature measurement technique called point contact spectroscopy (PCS) [2], their study revealed that the bridge is made up of metal atoms from both the electrode and the metal sulfide layer. This surprising finding controverts the prevailing notion that the bridge derives from the electrode only, Kiguchi explains.

The team compared atomic switches with different combinations of electrodes (Pt and Ag, or Pt and Cu) and metal sulfide layers (Cu2S and Ag2S). In both cases, they found that the bridge is mainly composed of Ag.

The reason behind the dominance of Ag in the bridge is likely due to “the higher mobility of Ag ions compared to Cu ions”, the researchers say in their paper published in ACS Applied Materials & Interfaces.

They conclude that “it would be better to use metals with low mobility” for designing atomic switches with higher stability.

Much remains to be explored in the advancement of atomic switch technologies, and the team is continuing to investigate which combination of elements would be the most effective in improving performance.


Technical terms
[1] Atomic switch: The idea behind an atomic switch — one that can be controlled by the motion of a single atom — was introduced by Donald Eigler and colleagues at the IBM Almaden Research Center in 1991. Interest has since focused on how to realize and harness the potential of such extremely small switches for use in logic circuits and memory devices. Over the past two decades, researchers in Japan have taken a world-leading role in the development of atomic switch technologies.
[2] Point contact spectroscopy: A method of measuring the properties or excitations of single atoms at low temperature.

Caption: The ‘bridge’ that forms within the metal sulfide layer, connecting two metal electrodes, results in the atomic switch being turned on. Credit: Manabu Kiguchi

Here’s a link to and a citation for the paper,

Investigation of Ag and Cu Filament Formation Inside the Metal Sulfide Layer of an Atomic Switch Based on Point-Contact Spectroscopy by A. Aiba, R. Koizumi, T. Tsuruoka, K. Terabe, K. Tsukagoshi, S. Kaneko, S. Fujii, T. Nishino, M. Kiguchi. ACS Appl. Mater. Interfaces 2019 XXXXXXXXXX-XXX DOI: https://doi.org/10.1021/acsami.9b05523 Publication Date:July 5, 2019 Copyright © 2019 American Chemical Society

This paper is behind a paywall.

For anyone who might need a bit of a refresher for the chemical elements, Pt is platinum, Ag is silver, and Cu is copper. So, with regard to the metal sulfide layers Cu2S is copper sulfide and Ag2S is silver sulfide.

Phenomen: a future and emerging information technology project

A Sept. 19, 2016 news item on Nanowerk describes a new research project incorporating photonics, phononics, and radio frequency signal processing,

HENOMEN is a ground breaking project designed to harness the potential of combined phononics, photonics and radio-frequency (RF) electronic signals to lay the foundations of a new information technology. This new Project, funded though the highly competitive H2020 [the European Union’s Horizon 2020 science funding programme] FET [Future and Emerging Technologies]-Open call, joins the efforts of three leading research institutes, three internationally recognised universities and a high-tech SME. The Consortium members kick-offed the project with a meeting on Friday September 16, 2016, at the Catalan Institute of Nanoscience and Nanotechnology (ICN2), coordinated by ICREA Research Prof Dr Clivia M. Sotomayor-Torres, of the ICN2’ Phononic and Photonic Nanostructures (P2N) Group.

A Sept. 16, 2016 ICN2 press release, which originated the news item, provides more detail,

Most information is currently transported by electrical charge (electrons) and by light (photons). Phonons are the quanta of lattice vibrations with frequencies covering a wide range up to tens of THz and provide coupling to the surrounding environment. In PHENOMEN the core of the research will be focused on phonon-based signal processing to enable on-chip synchronisation and transfer information carried between optical channels by phonons.

This ambitious prospect could serve as a future scalable platform for, e.g., hybrid information processing with phonons. To achieve it, PHENOMEN proposes to build the first practical optically-driven phonon sources and detectors including the engineering of phonon lasers to deliver coherent phonons to the rest of the chip pumped by a continuous wave optical source. It brings together interdisciplinary scientific and technology oriented partners in an early-stage research towards the development of a radically new technology.

The experimental implementation of phonons as information carriers in a chip is completely novel and of a clear foundational character. It deals with interaction and manipulation of fundamental particles and their intrinsic dual wave-particle character. Thus, it can only be possible with the participation of an interdisciplinary consortium which will create knowledge in a synergetic fashion and add value in the form of new theoretical tools,  develop novel methods to manipulate coherent phonons with light and build all-optical phononic circuits enabled by optomechanics.

The H2020 FET-Open call “Novel ideas for radically new technologies” aims to support the early stages of joint science and technology research for radically new future technological possibilities. The call is entirely non-prescriptive with regards to the nature or purpose of the technologies that are envisaged and thus targets mainly the unexpected. PHENOMEN is one of the 13 funded Research & Innovation Actions and went through a selection process with a success rate (1.4%) ten times smaller than that for an ERC grant. The retained proposals are expected to foster international collaboration in a multitude of disciplines such as robotics, nanotechnology, neuroscience, information science, biology, artificial intelligence or chemistry.

The Consortium

The PHENOMEN Consortium is made up by:

  • 3 leading research institutes:
  • 3 universities with an internationally recognised track-record in their respective areas of expertise:
  • 1 industrial partner: