Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Novel Topological Insulator

11.10.2018

For the first time, physicists have built a unique topological insulator in which optical and electronic excitations hybridize and flow together. They report their discovery in "Nature".

Topological insulators are materials with very special properties. They conduct electricity or light particles on their surface or edges only but not on the inside. This unusual behaviour could eventually lead to technical innovations which is why topological insulators have been the subject of intense global research for several years.


The novel topological insulator built in the Würzburg Institute of Physics: a controllable flow of hybrid optoelectronic particles (red) travels along its edges.

(Picture: Karol Winkler)

Physicists of Julius-Maximilians-Universität Würzburg (JMU) in Bavaria, Germany, with colleagues from the Technion in Haifa, Israel, and Nanyang Technological University in Singapore now report their discovery in the journal "Nature". For the first time, the team has successfully built a topological insulator operating with both light and electronic excitations simultaneously, called an “exciton-polariton topological insulator”.

Novelty with dual benefit

According to Professor Sven Höfling, who heads the JMU Chair for Applied Physics, such topological insulators have a dual benefit: "They could be used for both switched electronic systems and laser applications." The topological insulators developed previously are based on either electrons or photons, allowing only one of these applications to be implemented.

Dr. Sebastian Klembt, group leader at Höfling's chair, played a lead role in the project. He gives more details: The novel topological insulator was built on a microchip and basically consists of the gallium arsenide semiconductor compound. It has a honeycomb structure and is made up of many small pillars, each two micrometres (two millionths of a metre) in diameter.

Propagation direction can be controlled

When exciting this microstructure with laser light, light-matter particles form inside it, exclusively at the edges. The particles then travel along the edges and around the corners with relatively low loss. "A magnetic field enables us to control and reverse the propagation direction of the particles," Klembt says.

It is a sophisticated systems which works in application-oriented dimensions – on a microchip – and in which light can be controlled. Usually, this is not so easy to accomplish: Pure light particles have no electric charge and therefore cannot be readily controlled with electric or magnetic fields. The new topological insulator in contrast is capable of doing this by "sending light around the corner" in a manner of speaking.

JMU and Technion: expertise in topological insulators

This research success of Höfling's team shows once more that the University of Würzburg's Institute of Physics is a leading center of topological insulator research. In 2007, JMU Professor of Physics, Laurens Molenkamp, pioneered the field by experimentally building the world’s first topologically insulator. The Würzburg physicists' excellence in this field was again recognized recently in September 2018 with the awarding of a grant for the Excellence Cluster "Complexity and Topology in Quantum Materials" within the scope of the German "Excellence Strategy" competition.

The Technion scientists have complementary expertise: it is the group of Mordechai (Moti) Segev which has demonstrated the first photonic topological insulator, back in 2013, and launched the field of “Topological Photonics”. The groups have now joined forces to demonstrate this first symbiotic light-matter topological insulator, which holds great promise both as a fundamental discovery and by opening the door for exiting applications in optoelectronics.

Wissenschaftliche Ansprechpartner:

Dr. Sebastian Klembt, Chair for Applied Physics, JMU, T +49 931 31-85980, sebastian.klembt@physik.uni-wuerzburg.de

Prof. Dr. Sven Höfling, Chair for Applied Physics, JMU, T +49 931 31-83613, hoefling@physik.uni-wuerzburg.de

Originalpublikation:

“Exciton-polariton topological insulator”, S. Klembt, T. H. Harder, O. A. Egorov, K. Winkler, R. Ge, M. A. Bandres, M. Emmerling, L. Worschech, T. C. H. Liew, M. Segev, C. Schneider & S. Höfling, Nature, 8 October 2018, DOI 10.1038/s41586-018-0601-5

Robert Emmerich | Julius-Maximilians-Universität Würzburg
Further information:
http://www.uni-wuerzburg.de

More articles from Physics and Astronomy:

nachricht Spintronics: Researchers show how to make non-magnetic materials magnetic
06.08.2020 | Martin-Luther-Universität Halle-Wittenberg

nachricht Manifestation of quantum distance in flat band materials
05.08.2020 | Institute for Basic Science

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: ScanCut project completed: laser cutting enables more intricate plug connector designs

Scientists at the Fraunhofer Institute for Laser Technology ILT have come up with a striking new addition to contact stamping technologies in the ERDF research project ScanCut. In collaboration with industry partners from North Rhine-Westphalia, the Aachen-based team of researchers developed a hybrid manufacturing process for the laser cutting of thin-walled metal strips. This new process makes it possible to fabricate even the tiniest details of contact parts in an eco-friendly, high-precision and efficient manner.

Plug connectors are tiny and, at first glance, unremarkable – yet modern vehicles would be unable to function without them. Several thousand plug connectors...

Im Focus: New Strategy Against Osteoporosis

An international research team has found a new approach that may be able to reduce bone loss in osteoporosis and maintain bone health.

Osteoporosis is the most common age-related bone disease which affects hundreds of millions of individuals worldwide. It is estimated that one in three women...

Im Focus: AI & single-cell genomics

New software predicts cell fate

Traditional single-cell sequencing methods help to reveal insights about cellular differences and functions - but they do this with static snapshots only...

Im Focus: TU Graz Researchers synthesize nanoparticles tailored for special applications

“Core-shell” clusters pave the way for new efficient nanomaterials that make catalysts, magnetic and laser sensors or measuring devices for detecting electromagnetic radiation more efficient.

Whether in innovative high-tech materials, more powerful computer chips, pharmaceuticals or in the field of renewable energies, nanoparticles – smallest...

Im Focus: Tailored light inspired by nature

An international research team with Prof. Cornelia Denz from the Institute of Applied Physics at the University of Münster develop for the first time light fields using caustics that do not change during propagation. With the new method, the physicists cleverly exploit light structures that can be seen in rainbows or when light is transmitted through drinking glasses.

Modern applications as high resolution microsopy or micro- or nanoscale material processing require customized laser beams that do not change during...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“Conference on Laser Polishing – LaP 2020”: The final touches for surfaces

23.07.2020 | Event News

Conference radar for cybersecurity

21.07.2020 | Event News

Contact Tracing Apps against COVID-19: German National Academy Leopoldina hosts international virtual panel discussion

07.07.2020 | Event News

 
Latest News

Rare Earth Elements in Norwegian Fjords?

06.08.2020 | Earth Sciences

Anode material for safe batteries with a long cycle life

06.08.2020 | Power and Electrical Engineering

Turning carbon dioxide into liquid fuel

06.08.2020 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>