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:
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...