Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Strong and free electrons

01.03.2010
Long-predicted physical effects confirmed for the first time by a model system of strongly interacting electrons

From the study of an unusual two-dimensional electron system that is generated on the surface of low-temperature liquid helium, a RIKEN-led international research team has revealed that electrons free of atoms interact more strongly with each other than their counterparts in a semiconductor1.

The work provides valuable insights into both electron interactions and thin films of so-called ‘two-dimensional free electron gases’, which have useful applications. Low-noise amplifiers in mobile phone base stations, for example, use the electrical characteristics of weakly interacting two-dimensional electron gases in thin-film semiconductor devices.

The strong electron interaction observed by the researchers was evident once the free electrons were excited into a higher energetic state by microwave radiation. “As soon as the first electrons are in the higher state, the strong interaction between electrons in both states means that the energy difference between these two states changes as a result,” comments Denis Konstantinov from the research team.

This energy shift has been long predicted theoretically, although the weak electron interactions in semiconductors meant that it was too small to be observed. It is the strong electron interactions in the liquid helium system that enabled its detection for the first time. “It is due to its simplicity and extreme cleanness of our system that many theoretically predicted phenomena can be observed,” says Konstantinov.

The researchers then ventured to more complex experiments and applied a strong magnetic field perpendicular to the electron gas. This forced the electrons into a number of quantum states. As they increased the magnetic field, the energies of these quantum states shifted towards higher values. Successively, each quantum state changed to match the fixed energy of the higher energy surface state, again induced by the microwave radiation. At the matching condition, the electrical resistance of the quantum states increased owing to the interaction with the surface state. This resulted in characteristic oscillations in the electrical resistance with increasing magnetic field.

Konstantinov and colleagues also observed that in this configuration the strong interactions between the electrons can lead to a destruction of the quantum states and therefore to the complete disappearance of the resistance oscillations2.

At a more general level, however, the implications of these experiments are profound, and open a new arena for the study of such systems. Citing just one example, Konstantinov says that, “this is a model system to emulate quantum physical effects such as those explored for quantum computing.”

The corresponding author for this highlight is based at the Low Temperature Physics Laboratory, RIKEN Advanced Science Institute

Journal information

1. Konstantinov, D., Dykman, M. I., Lea, M. J., Monarkha, Y. & Kono, K. Resonant correlation-induced optical bistability in an electron system on liquid helium. Physical Review Letters 103, 096801 (2009)

2. Konstantinov, D. & Kono, K. Novel radiation-induced magnetoresistance oscillations in a nondegenerate two-dimensional electron system on liquid helium. Physical Review Letters 103, 266808 (2009)

Saeko Okada | Research asia research news
Further information:
http://www.rikenresearch.riken.jp/eng/research/6202
http://www.researchsea.com

More articles from Physics and Astronomy:

nachricht PPPL physicist uncovers clues to mechanism behind magnetic reconnection
24.01.2017 | DOE/Princeton Plasma Physics Laboratory

nachricht Electrocatalysis can advance green transition
23.01.2017 | Technical University of Denmark

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: Quantum optical sensor for the first time tested in space – with a laser system from Berlin

For the first time ever, a cloud of ultra-cold atoms has been successfully created in space on board of a sounding rocket. The MAIUS mission demonstrates that quantum optical sensors can be operated even in harsh environments like space – a prerequi-site for finding answers to the most challenging questions of fundamental physics and an important innovation driver for everyday applications.

According to Albert Einstein's Equivalence Principle, all bodies are accelerated at the same rate by the Earth's gravity, regardless of their properties. This...

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Arctic melt ponds form when meltwater clogs ice pores

24.01.2017 | Earth Sciences

Synthetic nanoparticles achieve the complexity of protein molecules

24.01.2017 | Life Sciences

PPPL physicist uncovers clues to mechanism behind magnetic reconnection

24.01.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>