Usually, the movement of electrons in a real material is rather different from the flow of water in a river. However, in extraordinary materials like the metal oxide PdCoO2, “electron rivers” can exist, as predicted theoretically over fifty years ago and now demonstrated by scientists from the MPI CPfS.
Although one might think that when there is an electric current in a metal, the electrons flow like water would in a pipe, that is actually not the case. Their motion is impeded because they bounce off the atoms that make up the metallic crystal, and the flow process is not nearly as interesting as the ones that we can see at play any time we sit next to a river.
For ‘electron rivers’ to exist, one needs to find extraordinary materials in which the collisions with the host atoms are thousands of times weaker than usual. Although this possibility, known as ‘electronic hydrodynamics’, was predicted theoretically over fifty years ago, it has taken until now to reach the new regime in a bulk material.
In Science Magazine (volume 351, 4th March 2016; see also the article “Perspectives” by J. Zaanen), three papers simultaneously reported experimental success. The groups of Philip Kim at Harvard and Andre Geim at Manchester worked on graphene, but the contribution from the Mackenzie and Moll groups from the Max Planck Institute for Chemical Physics of Solids Dresden was based on an oxide metal.
Our material of choice, PdCoO2, has an astonishingly high electrical conductivity, making it possible to look for hydrodynamic effects. To reveal their presence, we sculpted successively narrower channels, and studied how easily the electrons could flow through them.
By combining our results with a special theory that is able to model hydrodynamic effects, we were able to show that we had indeed created the long-predicted electron rivers. The research opens new frontiers in research into electron behavior in ultra-pure materials.
The richness seen in the flow of water might be observable in the flow of electrons, and some of this richness might one day also lead to the invention of new electronic devices. We hope to play a leading role in these developments.
The research at the Max Planck Institute for Chemical Physics of Solids (MPI CPfS) in Dresden aims to discover and understand new materials with unusual properties. In close cooperation, chemists and physicists (including chemists working on synthesis, experimentalists and theoreticians) use the most modern tools and methods to examine how the chemical composition and arrangement of atoms, as well as external forces, affect the magnetic, electronic and chemical properties of the compounds. New quantum materials, physical phenomena and materials for energy conversion are the result of this interdisciplinary collaboration.
The MPI CPfS (www.cpfs.mpg.de) is part of the Max Planck Society and was founded in 1995 in Dresden. It consists of around 280 employees, of which about 180 are scientists, including 70 doctoral students.
Ingrid Rothe | Max-Planck-Institut für Chemische Physik fester Stoffe
New design improves performance of flexible wearable electronics
23.06.2017 | North Carolina State University
Plant inspiration could lead to flexible electronics
22.06.2017 | American Chemical Society
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
23.06.2017 | Physics and Astronomy
23.06.2017 | Physics and Astronomy
23.06.2017 | Information Technology