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
In borophene, boundaries are no barrier
17.07.2018 | Rice University
Research finds new molecular structures in boron-based nanoclusters
13.07.2018 | Brown University
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
17.07.2018 | Power and Electrical Engineering