For decades, insulating materials were thought to be "boring" materials from an electronics point of view, since electrons are immobile and cannot contribute to electrical conduction. Recently, a different class of insulators was proposed and experimentally found. We call them "topological insulators", as their electronic structure can be mathematically classified to be different than the usual, boring, "trivial" insulators.
A fascinating property of topological insulators is that while remaining insulating in the bulk, they are very good conductors at the edge. At those edges, electrons travel in quantum channels in either direction, like in a two- lane highway.
Schematic representation of the electronic behavior in the device described in the article. The arrows represent quantum channels where electrons propagate. Eectrons are allowed to change direction only at the central area, resulting under certain conditions in constructive interference.
Credit: CIC nanoGUNE
Also like on a highway, U-turns are forbidden: electrons on the edge cannot change direction without breaking the rules. The application of an external magnetic field lifts this prohibition and allows electrons to turn.
The recently published research, lead by Reyes Calvo, Ikerbasque Fellow at CIC nanoGUNE, and Fernando de Juan, currently at Rudolf Peierls Centre for Theoretical Physics, Oxford and joining the Donostia International Phisics Centre (DIPC) as Ikerbasque Fellow in 2018, reports the interplay of quantum edge states across a lateral junction in a HgTe quantum well, a canonical 2D topological insulator.
From their results, they extract new information on the fundamental properties of topological edge states and propose strategies to fine-tune their interaction.
"In our work, we test the consequences that allowing electrons to turn have in the conduction of our devices. We also show how under certain circumstances, electrons allowed to return seem to do it in an orderly manner, as if in some kind of round-about, generating a constructive interference.", Calvo explains.
This work contributes new insight into the fundamental properties of the edge states and their conduction properties in 2D-topological insulators.
This kind of proposals to control the properties and interactions of these states are key for their application in the development of a new generation of electronic devices based on quantum fundamental properties of materials.
Irati Kortabitarte | EurekAlert!
From the cosmos to fusion plasmas, PPPL presents findings at global APS gathering
13.11.2018 | DOE/Princeton Plasma Physics Laboratory
A two-atom quantum duet
12.11.2018 | Institute for Basic Science
Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.
Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...
Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.
In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...
On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.
When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure
Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...
Physicists at ETH Zurich demonstrate how errors that occur during the manipulation of quantum system can be monitored and corrected on the fly
The field of quantum computation has seen tremendous progress in recent years. Bit by bit, quantum devices start to challenge conventional computers, at least...
09.11.2018 | Event News
06.11.2018 | Event News
23.10.2018 | Event News
14.11.2018 | Life Sciences
14.11.2018 | Earth Sciences
14.11.2018 | Medical Engineering