Normally, electrons, the carriers of an electrical charge, crisscross through metals or other electrically conductive materials. But this situation changes as the conductors are made smaller and smaller.
In nanowires made from gold atoms, electrons can only move in very narrow lanes, resulting in congestion. This is illustrated here by the red-stained wire. Depicted at the top right is the tip of a scanning tunneling microscope used by physicists to measure the electronic properties of nanowires. Image: Christian Blumenstein
Atomic building block: single gold atoms automatically form nanowires (left), which can then be connected deliberately using bridges or intentionally disrupted – by integrating other types of atom, for example, or by removing single gold atoms from the chains. Image: Christian Blumenstein
Würzburg physicists under Professor Ralph Claessen have taken miniaturization to the extreme: their nanowires consist of single gold atoms arranged in chains – it is not possible to go any smaller than that. In collaboration with Professor René Matzdorf from the University of Kassel and Luc Patthey from the Paul Scherrer Institute near Zurich, they have now examined the electrical properties of these nanowires.
In the nanowires, the electrons are so congested that they can only move in one direction, namely along the wires. And even this bit of freedom cannot be exploited to the full. They only move along in a stop-and-go manner, just like cars in a jam on the freeway with just one lane at their disposal: only when one car in the line of traffic moves forward a bit can the others do likewise. “The movements of the electrons in a nanowire are correlated just like this,” says Matzdorf. “This means they can only absorb selected energies, which is reflected in electrical conductivity and which we have measured precisely in an experiment.”
Publication in “Nature Physics”
This electron jam has now been proven experimentally by Claessen’s team in collaboration with their colleagues from Kassel and the Paul Scherrer Institute. The scientists achieved this using highly sensitive measuring techniques, scanning tunneling microscopy, and photoemission. This enabled them to verify the unusual states of the electrons directly. Their findings have been published in “Nature Physics”.
Why is a leading journal reporting the results of this research? “Because in atom chains we now have previously unknown capabilities for measuring the properties of a one-dimensional quantum liquid,” says Claessen. Physicists speak of a quantum liquid when the electrons are confined in such narrow lanes. Theoreticians predicted the properties of this “liquid” back in the 1960s. But very few of them have actually been observed in experiments as well, until now.
Nanowires as the basis for success
It has taken decades to generate these special electron states experimentally in atomic nanostructures. “This is mainly due to the fact that the nanowires produced previously were too close together and influenced each other, preventing the creation of a quantum liquid,” explains Claessen’s colleague, Jörg Schäfer.
The Würzburg physicists resolved this problem a good two years ago: using a sophisticated procedure, they vapor deposit gold atoms onto germanium plates such that they automatically arrange themselves into parallel linear chains far enough apart from one another.
Next steps in the research
The physicists now want to use the nanowires as an atomic building block. They are thinking, for example, of inserting contacts between the wires consisting of single atoms or molecules, which would equate to tiny atomic switching elements. The intention behind this is to explore other electronic phenomena at this smallest possible scale. Their findings may well prove very valuable to the rapid miniaturization of electronic components for computers, for example.
“Atomically controlled quantum chains hosting a Tomonaga-Luttinger liquid”, C. Blumenstein, J. Schäfer, S. Mietke, S. Meyer, A. Dollinger, M. Lochner, X. Y. Cui, L. Patthey, R. Matzdorf, R. Claessen, Nature Physics, Advanced Online Publication, August 7, 2011, DOI: 10.1038/nphys2051
Prof. Dr. Ralph Claessen, Institute of Physics at the University of Würzburg, T +49 (0)931 31-85732, email@example.com
Dr. Jörg Schäfer, Institute of Physics at the University of Würzburg, T +49 (0)931 31-83483, firstname.lastname@example.org
Prof. Dr. René Matzdorf, Institute of Physics at the University of Kassel, T +49 (0)561 804-4772, email@example.com
Robert Emmerich | Uni Würzburg
Pinball at the atomic level
30.03.2017 | Max-Planck-Institut für Struktur und Dynamik der Materie
Igniting a solar flare in the corona with lower-atmosphere kindling
29.03.2017 | New Jersey Institute of Technology
The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.
To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
29.03.2017 | Materials Sciences
29.03.2017 | Physics and Astronomy
29.03.2017 | Earth Sciences