Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The hidden Nano Power Switch: Kiel researchers discover switching function in molecular wire

27.10.2017

The increasing miniaturisation in electronics will result in components which consist of only a few molecules, or even just one molecule. An international research team from Kiel University (CAU) and the Donostia International Physics Center in San Sebastián/Spain, has developed a molecule integrating a wire with a diameter of only a single atom. They discovered that the current can be regulated via this molecular wire. It works like a nano power switch, and makes the use of molecular wires in electronic components at the nano scale feasible. The research team’s findings appeared in the scientific journal Physical Review Letters.

The wire produced by the scientists from Kiel and San Sebastián is just two atomic bonds long and one atom wide. "This is the simplest molecular wire imaginable, thinner and much shorter is not possible," explained the Kiel physicist Torben Jasper-Tönnies, first author of the publication.


How the wire molecule becomes a nano switch: the closer the tip of the scanning tunnelling microscope (yellow) gets to the nano wire (blue), the more the wire bends - and the current flow changes.

Copyright: Jasper-Tönnies


Torben Jasper-Tönnies placed a single atom at the tip of the scanning tunnelling microscope and was able to join a tiny wire with a diameter of just one atom to an electrical circuit.

Photo: Siekmann/CAU

In order to measure the current flowing through the nano wire, both ends must be connected to a metal electrode - like with larger circuits. But there are no metal clips which are small enough to create electrical contacts at the nano scale.

"Electrically contacting individual molecules in a nano circuit is a problem that has not yet been solved satisfactorily, and is widely discussed in the research community," explained Jasper-Tönnies, who is writing his doctoral thesis in the working group of Professor Richard Berndt.

In order to enable an electrical contact, the scientists developed a new wire, consisting of only a single molecule. "The special thing about our wire is that we can install it in a vertical position on a metal surface. This means that one of the two required contacts is already effectively built-in to the wire," explained Jasper-Tönnies.

To achieve this, the involved chemists used an approach from the Kiel Collaborative Research Centre (SFB) 677 “Function by Switching”. In the interdisciplinary research network, molecular platforms are among the areas of interest. The wire is attached to such a platform. It exhibits a high conductance, and can be easily attached to a metal surface like a suction cup - an electrical contact is realized.

For the second required contact, the research team used a scanning tunnelling microscope (STM). With a metal tip, it "feels" a sample, and creates an image of its surface on a scale down to a few nanometres. Individual atoms thus become visible. In their experiments, the Kiel researchers used a particularly fine metal tip for the STM, at the end of which was only a single atom.

In this way, they were able to create an electrical contact with the second end of the wire, close the circuit, and measure the current. "Through this very precise contact via just one atom, we obtained particularly good data. We can replicate these contacts, and the current values measured differ very little from wire to wire," said Jasper-Tönnies.

During their measurements, the researchers also found that quantum mechanical forces act between the metal tip of the STM and the nano wire. These can be used to bend the wire mechanically. If the wire is only slightly bent, the current is reduced. However, if there is a strong bend, it increases. "By bending the wire, we were able to switch the current on or off. Although our wire is so simple, it behaves in a very complex way - this surprised us," explained Jasper-Tönnies.

The scientists think that the unusual electrical conductance of the nano wire is caused by its molecular structure. This is supported by calculations performed by Dr. Aran Garcia-Lekue and Professor Thomas Frederiksen from San Sebastián. As a result of the quantum mechanical forces, the individual atoms of the wire form new chemical bonds with the atom at the tip of the STM probe. This changes the geometry of the molecule, and thereby its properties. “Small geometrical differences can actually have a huge effect. This is why it is important to be able to set the geometry of a molecule and measure it as accurately as possible - and we achieve this by the precise contact of the nano wire and via the STM images in atomic resolution," said Jasper-Tönnies.

The publication of the researchers from Kiel and San Sebastián was highly recommended by the editors of Physical Review Letters as their "Editors' suggestion".

Original publication
Conductance of a Freestanding Conjugated Molecular Wire, Torben Jasper-Tönnies, Aran Garcia-Lekue, Thomas Frederiksen, Sandra Ulrich, Rainer Herges, Richard Berndt. Phys. Rev. Lett. 119, 2017, 066801
https://doi.org/10.1103/PhysRevLett.119.066801

Photos are available to download:

http://www.uni-kiel.de/download/pm/2017/2017-330-1.jpg
Caption: Torben Jasper-Tönnies meticulously placed a single atom at the tip of the scanning tunnelling microscope at the Institute of Experimental and Applied Physics. The effort was worth it: the physicist was then able to join a tiny wire with a diameter of just one atom to an electrical circuit.
Photo: Siekmann/CAU

http://www.uni-kiel.de/download/pm/2017/2017-330-2.png
Caption: The top view shows: just one atom wide - less than a nanometre - is the wire (green), which is mounted vertically on a conductive platform (red). It can be easily attached to a metal surface (dark) like a suction cup - an electrical contact is realized.
Copyright: Jasper-Tönnies

http://www.uni-kiel.de/download/pm/2017/2017-330-3.png
Caption: This is how the wire molecule becomes a nano switch: the closer the tip of the scanning tunnelling microscope (yellow) gets to the nano wire (blue), the more the wire bends - and the current flow changes. This is due to quantum mechanical forces acting between the tip and the wire. They change the geometry of the molecule, and thereby its properties.
Copyright: Jasper-Tönnies

Contact:
Dipl.-Phys. Torben Jasper-Tönnies
Institute of Experimental and Applied Physics
Tel.: +49 (0)431/880-3834
E-mail: jasper-toennies@physik.uni-kiel.de

Kiel University
Press, Communication and Marketing, Dr Boris Pawlowski, Text/editing: Julia Siekmann
Postal address: D-24098 Kiel, Germany,
Telephone: +49 (0)431 880-2104, Fax: +49 (0)431 880-1355
E-mail: presse@uv.uni-kiel.de, Internet: www.uni-kiel.de, Twitter: www.twitter.com/kieluni Facebook: www.facebook.com/kieluni, Instagram: www.instagram.com/kieluni

The Collaborative Research Centre (SFB) 677 “Function by Switching” at Kiel University, has around 100 scientists from Chemistry, Physics, Materials Science, Pharmacy and Medicine working on a cross-disciplinary basis to develop switchable molecular machines which can be controlled by light, for example. The CRC has been financed by the German Research Foundation (DFG) since 2007. More information: http://www.sfb677.uni-kiel.de

Dr. Boris Pawlowski | Christian-Albrechts-Universität zu Kiel

More articles from Life Sciences:

nachricht ADP-ribosylation on the right track
26.04.2018 | Max-Planck-Institut für Biologie des Alterns

nachricht Flavins keep a handy helper in their pocket
25.04.2018 | University of Freiburg

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Why we need erasable MRI scans

New technology could allow an MRI contrast agent to 'blink off,' helping doctors diagnose disease

Magnetic resonance imaging, or MRI, is a widely used medical tool for taking pictures of the insides of our body. One way to make MRI scans easier to read is...

Im Focus: BAM@Hannover Messe: innovative 3D printing method for space flight

At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.

Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Why we need erasable MRI scans

26.04.2018 | Medical Engineering

Balancing nuclear and renewable energy

26.04.2018 | Power and Electrical Engineering

Researchers 3-D print electronics and cells directly on skin

26.04.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>