Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Topological Nanoelectronics

29.10.2019

Physicists at the University of Würzburg have made a ground-breaking discovery: They have realized a fundamental nanoelectronic device based on the topological insulator HgTe previously discovered in Würzburg.

Topological insulators are materials with astonishing properties: Electric current flows only along their surfaces or edges, whereas the interior of the material behaves as an insulator. In 2007, Professor Laurens Molenkamp at Julius-Maximilians-Universität (JMU) Würzburg in Bavaria, Germany, was the first who experimentally demonstrated the existence of such topological states.


A quantum well narrows in the middle to a quantum point contact. Würzburg physicists have produced this device using new methods of nanostructuring.

Picture: Christoph Fleckenstein / University of Wuerzburg

His team achieved this seminal work with quantum wells based on mercury and tellurium (HgTe). Since then, these novel materials have been the hope for a fundamentally new generation of components that, for example, promise innovations for information technology.

Physicists at JMU have now succeeded for the first time in constructing an essential element for such components – a Quantum Point Contact (QPC). They present this achievement in a recent publication in the journal Nature Physics.

Confinement for topological states

Quantum point contacts are quasi one-dimensional constrictions in otherwise two-dimensional structures that are only a few atomic layers thin. In topological HgTe quantum wells, in which the conducting states are located exclusively at the edges, these edge states are spatially merged at the QPC. This proximity makes it possible to investigate potential interactions between the edge states.

"This experiment could only work because of a breakthrough in our lithographic methods. It has enabled us to create incredibly small structures without damaging the topological material. I am convinced that this technology will enable us to find impressive, novel effects in topological nanostructures in the near future," said Molenkamp.

Anomalous conductance behavior through interaction

Using a sophisticated manufacturing process, the JMU physicists have succeeded in structuring the bottleneck particularly precisely and gently. This technological progress allowed them to functionalize the topological properties of the system.

In this context, the team led by Professors Laurens Molenkamp and Björn Trauzettel was able to demonstrate for the first time ever interaction effects between the different topological states of a system using anomalous conductance signatures. The Würzburg researchers attribute this particular behaviour of the analyzed topological QPCs to the physics of one-dimensional electronic systems.

Interacting electrons in one dimension

If electronic correlations are analysed in one spatial dimension, electrons move – unlike in two or three spatial dimensions –in a well-ordered manner because there is no possibility of „overtaking“ the leading electron. Pictorially speaking, the electrons in this case behave like pearls on a chain.

This special property of one-dimensional systems leads to interesting physical phenomena. Trauzettel says: "The interplay of strong Coulomb interaction and spin orbit coupling is rare in nature. I therefore expect this system to yield fundamental discoveries in the coming years".

Outlook for future research

Topological QPCs are an elementary component for many applications that have been predicted in theory in recent years.

A particularly prominent example of this kind is the possible realization of Majorana fermions, which the Italian physicist Ettore Majorana predicted back in 1937. A promising application potential in connection with topological quantum computers is attributed to these excitations.

For this purpose, it is of great importance not only to detect Majorana fermions, but also to be able to control and manipulate them at will. The topological QPC, first implemented at JMU Würzburg, offers an exciting perspective in this respect.

Wissenschaftliche Ansprechpartner:

Prof. Dr. Laurens Molenkamp, Institute for Topological Isolators, University of Würzburg, T +49 931 31-84925, molenkamp@physik.uni-wuerzburg.de

Prof. Dr. Björn Trauzettel, Chair of Theoretical Physics IV, University of Würzburg, T +49 931 31-83638, trauzettel@physik.uni-wuerzburg.de

Originalpublikation:

Interacting topological edge channels, Nature Physics, 28 October 2019, DOI: 10.1038/s41567-019-0692-4

Robert Emmerich | Julius-Maximilians-Universität Würzburg

More articles from Physics and Astronomy:

nachricht Images from NJIT's big bear solar observatory peel away layers of a stellar mystery
18.11.2019 | New Jersey Institute of Technology

nachricht A one-way street for light
15.11.2019 | Rheinische Friedrich-Wilhelms-Universität Bonn

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: Images from NJIT's big bear solar observatory peel away layers of a stellar mystery

An international team of scientists, including three researchers from New Jersey Institute of Technology (NJIT), has shed new light on one of the central mysteries of solar physics: how energy from the Sun is transferred to the star's upper atmosphere, heating it to 1 million degrees Fahrenheit and higher in some regions, temperatures that are vastly hotter than the Sun's surface.

With new images from NJIT's Big Bear Solar Observatory (BBSO), the researchers have revealed in groundbreaking, granular detail what appears to be a likely...

Im Focus: New opportunities in additive manufacturing presented

Fraunhofer IFAM Dresden demonstrates manufacturing of copper components

The Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM in Dresden has succeeded in using Selective Electron Beam Melting (SEBM) to...

Im Focus: New Pitt research finds carbon nanotubes show a love/hate relationship with water

Carbon nanotubes (CNTs) are valuable for a wide variety of applications. Made of graphene sheets rolled into tubes 10,000 times smaller than a human hair, CNTs have an exceptional strength-to-mass ratio and excellent thermal and electrical properties. These features make them ideal for a range of applications, including supercapacitors, interconnects, adhesives, particle trapping and structural color.

New research reveals even more potential for CNTs: as a coating, they can both repel and hold water in place, a useful property for applications like printing,...

Im Focus: Magnets for the second dimension

If you've ever tried to put several really strong, small cube magnets right next to each other on a magnetic board, you'll know that you just can't do it. What happens is that the magnets always arrange themselves in a column sticking out vertically from the magnetic board. Moreover, it's almost impossible to join several rows of these magnets together to form a flat surface. That's because magnets are dipolar. Equal poles repel each other, with the north pole of one magnet always attaching itself to the south pole of another and vice versa. This explains why they form a column with all the magnets aligned the same way.

Now, scientists at ETH Zurich have managed to create magnetic building blocks in the shape of cubes that - for the first time ever - can be joined together to...

Im Focus: A new quantum data classification protocol brings us nearer to a future 'quantum internet'

The algorithm represents a first step in the automated learning of quantum information networks

Quantum-based communication and computation technologies promise unprecedented applications, such as unconditionally secure communications, ultra-precise...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

First International Conference on Agrophotovoltaics in August 2020

15.11.2019 | Event News

Laser Symposium on Electromobility in Aachen: trends for the mobility revolution

15.11.2019 | Event News

High entropy alloys for hot turbines and tireless metal-forming presses

05.11.2019 | Event News

 
Latest News

Volcanoes under pressure

18.11.2019 | Earth Sciences

Scientists discover how the molecule-sorting station in our cells is formed and maintained

18.11.2019 | Life Sciences

Hot electrons harvested without tricks

18.11.2019 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>