Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Molecular chains hypersensitive to magnetic fields

05.07.2013
Nanoscientists Twente, Strasbourg and Eindhoven publish in top scientific journal Science

Researchers of MESA+, the research institute for nanotechnology of the University of Twente, in cooperation with researchers of the University of Strasbourg and Eindhoven University of Technology, are the first to successfully create perfect one-dimensional molecular wires of which the electrical conductivity can almost entirely be suppressed by a weak magnetic field at room temperature.


A conducting-probe atomic force microscope (CP-AFM) measures the electrical conduction of aromatic molecules, DXP, aligned within the channels of a zeolite crystal on top of a conducting substrate. The channels have a maximum diameter of 1.26 nanometer and an entrance diameter of only 0.71 nanometer; the DXP molecules have the same width as the channel entrances and a length of 2.2 nanometers. Therefore, the entrapped molecules are all aligned along the zeolite channel axis, forming perfectly one-dimensional molecular wires. The zoom-in shows a DXP molecule confined in a zeolite channel. The IUPAC chemical name of DXP is N,N'-bis(2,6-dimethylphenyl)-perylene-3,4,9,10-tetracarboxylic diimide.

Credit: MESA+


Zeolite L is an electrically insulating aluminosilicate crystalline system, which consists of many channels running through the whole crystal and oriented parallel to the cylinder axis. The geometrical constraints of the zeolite host structure allow for the formation of one-dimensional chains of highly uniaxially oriented molecules.

Credit: MESA+

The underlying mechanism is possibly closely related to the biological compass used by some migratory birds to find their bearings in the geomagnetic field. This spectacular discovery may lead to radically new magnetic field sensors, for smartphones for example. The leading scientific journal Science publishes the research results on 4 July.

In their experiments, the researchers made use of DXP, the organic molecule which is a red dye of the same type as once used by Ferrari for their famous Testarossa. In order to thread the molecules so that they form one-dimensional chains of 30 to 100 nanometers in length - 1 nanometer being 1 billionth of a meter - they applied a smart trick: they locked the molecules in zeolite crystals. Zeolites are porous minerals composed of silicon, aluminum and oxygen atoms with narrow channels, like the lift shafts in a block of flats. The diameter of the channels in the zeolites is only 1 nanometer, just a little wider than the molecule's diameter. This enabled the researchers to create chains of aligned molecules inside the zeolite channel, which are only 1 molecule wide.

Molecular electric wires
The zeolite crystals containing the molecular wires were then placed on an electricity-conductive substrate. By placing a very sharp conductive needle, of an atomic force microscope (AFM), on top of a zeolite crystal, the researchers were able to measure the electrical conductivity in the molecule chains. Professor Wilfred van der Wiel, who developed and led the experiment, says that measuring the electrical conductivity in these molecular electric wires is a unique result in itself. "But the behavior of these wires is simply spectacular when applying a magnetic field," he adds. This is because electrical conductivity nearly completely breaks down in a magnetic field of just a few milliteslas in size, a field which you could easily generate with a refrigerator magnet. Van der Wiel: "The fact that the effect is so dramatic and occurs even in small magnetic fields at room temperature makes this result very special."

Single-lane road

The change in electrical resistance through a magnetic field is called magnetoresistance and is very important in technology. It is also used in hard disk read heads. Usually, magnetic materials are indispensable for creating magnetoresistance. However, the ultra-high magnetoresistance which has been measured in Twente was achieved without any magnetic materials. The researchers ascribe this effect to the interaction between the electrons carrying electricity and the magnetic field which is generated by the surrounding atomic nuclei in the organic molecules. Current suppression in a small magnetic field can ultimately be traced back to the famous Pauli exclusion principle, the quantum mechanical principle that states that no two electrons (fermions) may have identical quantum numbers. Since the electric wires are essentially one-dimensional, the effect of the Pauli exclusion principle is dramatic, comparable to an accident on a single-lane road that brings traffic to a standstill. This interpretation is supported by calculations.

Migratory birds
The mechanism that is responsible for ultra-high magnetoresistance in molecular wires is possibly closely related to the biological compass used by some migratory birds to find their bearings in the geomagnetic field. Researchers of the University of Twente are conducting follow-up experiments in the hope to be able to shed more light on this analogy.

Research

The research has been conducted by scientists of the Chair NanoElectronics of the MESA+ Institute for Nanotechnology, in close collaboration with researchers of Eindhoven University of Technology and the University of Strasbourg. On 4 July, the leading scientific journal Science publishes the article 'Ultra-High Magnetoresistance at Room Temperature in Molecular Wires' in which the research results are described in more detail. This research has been made possible by funding from the STW Technology Foundation and the European Union.

Note to the press

For more information, interview requests or a digital copy of the article 'Ultra-High Magnetoresistance at Room Temperature in Molecular Wires', please contact the University of Twente Science Information Officer Joost Bruysters (+31 (0)6 1048 8228) or prof. Wilfred van der Wiel (+31 (0)6 3018 2641).

Joost Bruysters | EurekAlert!
Further information:
http://www.utwente.nl

More articles from Life Sciences:

nachricht Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery
20.01.2017 | GSI Helmholtzzentrum für Schwerionenforschung GmbH

nachricht Seeking structure with metagenome sequences
20.01.2017 | DOE/Joint Genome Institute

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Helmholtz International Fellow Award for Sarah Amalia Teichmann

20.01.2017 | Awards Funding

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>