Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Crystal of holes discovered

06.12.2005


Physicists at Kiel University discover an unusual state of matter



The existence of an unusual state of matter, a crystal that consists entirely of holes, has been proven at Kiel University. As reported in the latest issue of Physical Review Letters (December 2nd , 2005), an international team led by Professor Michael Bonitz has, for the first time, demonstrated with the help of extensive computer simulations that this exotic phenomenon, the existence of which was hitherto only a subject of speculation, should certainly occur. The physicists have also been able to predict the conditions for its formation.

"We now know that this effect occurs in semiconductors with a certain type of band structure", says Bonitz. "In normal solids, the electrons and holes (which are formed when electrons are excited) are both far extended inside the solid - a consequence of quantum mechanics. Electrons and holes penetrate the material like a liquid". However, when the mass of a hole exceeds a certain critical value - 80 times the mass of an electron - the hole liquid undergoes a spontaneous change to become a crystal. Furthermore, there are strong indications that in semiconductor systems of this kind, a reduction of pressure can result in the formation of Bose condensates of bound electron-hole pairs (so-called excitons). Anticipating the next stage of the research, the physicist explains that "the next exciting problem is to set up an experiment that will confirm our prediction of the crystal of holes". Suitable materials systems for this have already been suggested.


The scientist at the Institute of Theoretical Physics and Astrophysics explains that the crystal of holes is also of great interest for another reason: "We have been able to show that it has many features in common with very different kinds of crystals, such as plasma crystals or ionic crystals". It is especially intriguing that the crystal of holes shows many similarities with some of the most mysterious objects in the universe - white dwarfs and neutron stars. It has been suggested that a crystal of nuclei exists in these exotic, very distant objects. Bonitz hopes that "it may soon be possible to study important properties of these systems in the laboratory by experiments on a crystal of holes".

This extraordinary kind of crystal may also be of interest for materials research, says Bonitz, "because it may possess properties of importance for superconductivity". Whereas superconductivity (a flow of electrical current with no resistance) can only be achieved at present at very low temperatures, some scientists, in particular the 2003 Physics Nobel Prize winner Alexei Abrikosov, expect that systems containing a crystal of holes should become superconducting at significantly higher temperatures. This presents the Kiel scientists and their partners with a challenge, and Bonitz comments that "an important aim of our continuing investigations will be to test these predictions".

In his research, Professor Michael Bonitz is collaborating with a German-Russian team of scientists, which includes Professor Holger Fehske (Greifswald University) and Dr. Vladimir S. Filinov (Institute for High Energy Density, Moscow). The project forms a part of the Transregional Collaborative Research Centre TR 24, on "Fundamentals of Complex Plasmas", which was recently approved by the Deutsche Forschungsgemeinschaft (German Research Foundation), and is based at the universities of Greifswald and Kiel.

The research results haven been selected by the American Physics Society for coverage in its online journal Physical Review Focus, see http://focus.aps.org/story/v16/st17

Susanne Schuck | alfa
Further information:
http://www.uni-kiel.de/aktuell/pm/2005/2005-126-lochkristall-e.shtml

More articles from Physics and Astronomy:

nachricht Climate cycles may explain how running water carved Mars' surface features
02.12.2016 | Penn State

nachricht What do Netflix, Google and planetary systems have in common?
02.12.2016 | University of Toronto

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

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...

Im Focus: Quantum Particles Form Droplets

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...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

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,...

Im Focus: Molecules change shape when wet

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...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

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...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>