A mysterious change in the wave properties of electrons
The electrons of a perfect metallic surface move like free waves in a plane. Nevertheless, if atomic barriers are inserted, this may restrict their movement in one dimension, forming stationary waves such as those on the water surface in a bucket.
The stationary or free behaviour of electron waves is, nevertheless, still something very intriguing, given that the barriers of atoms are very close to each other, there is no confinement, and that the electron recovers its free movement, exactly as was discovered some years ago by the Nanophysics Laboratory research team led by Enrique Ortega at the Donostia-San Sebastian campus of the University of the Basque Country.
The prestigious magazine Physical Review Letters, the most important in the world in the field of Physics, has just published the results of new research this team has been undertaking since 1999 on the wave properties of electrons: the critical size of the step is 2 nanometres, i.e., if the distance of the barriers is superior to 2 nanometres, the electrons form stationary waves; if it is inferior, the waves are free.
More specifically, Enrique Ortega has formed a new nanostructure, i.e. a typical nanometre-sized structure (a nanometre being a thousand millionth or a billionth of a metre) by depositing small quantities of silver on a copper surface. The system arranges itself by forming a network of nanostrips of silver and copper. The copper strips show atomic steps with a step width that depends on the amount of silver deposited. On varying the width, one can observe in detail the transformation of the stationary waves confined between the steps of atomic height in waves of electrons that move freely.
In this way the critical size of the step of 2 nanometres has been discovered: less than this width free waves exist and widths greater than this critical figure are confined. “The detailed study of this transition will be fundamental in the future when establishing the wave properties of electrons in metallic nanostructures", stated Enrique Ortega.
According to Doctor Ortega, the most difficult part of the investigation was constructing the system by which the measurement was to be carried out. These kinds of trials have to be undertaken in ultra high vacuum systems, where not even the smallest particle can be present, as the least amount of contamination will destroy the system. They are also systems difficult to extract information from. Moreover, it is necessary to create a structure limited to a width of 4 or 5 atoms, controlling all the parameters at the same time, demanding a complex prior process.
This is the sixth time that Dr Ortega, leader of the only experimental physics group working on nanostructures in Euskadi, has published an article in Physical Review Lettersz. Regarding the applications for the discovery, the researcher points out that “although, in the field of nanoscience, one always has to go through a number of phases, we cannot discard its utility, certainly in the field of what will be the electronics of the future - nanoelectronics”.
Garazi Andonegi | alfa
The most recent press releases about innovation >>>
Die letzten 5 Focus-News des innovations-reports im Überblick:
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
New technique promises tunable laser devices
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...