Topological Insulator

A topological insulator is a material with non-trivial topological order that behaves as an insulator in its interior but whose surface contains conducting states, meaning that electrons can only move along the surface of the material.

  • Added Disorder Drives Transition to Photonic Topological Insulator

    A honeycomb waveguide structure with helical waveguides acts as a photonic topological insulator so that light is guided along the surface. Copyright: University of Rostock/Alexander Szameit, Lukas Maczewsky

    As the journal Nature reported recently, a research group led by the Rostock physicist Professor Alexander Szameit, in collaboration with colleagues in Israel and the U.S., experimentally demonstrated that a messy topological insulator can be restored in its properties by inducing random disorder.

  • Aufruhr auf der Nanoskala – Topologische Isolatoren leisten Widerstand

    Die kleine Kante ist nur rund fünf Atomschichten dick, doch sie reicht aus, um eine feste Theorie ins Wanken zu bringen: An Topologischen Isolatoren, den Hoffnungsträgern z.B. für Quantencomputer, forschen Projektleiter Dr. Christian Bobisch und Sebastian Bauer vom Center for Nanointegration (CENIDE) der Universität Duisburg-Essen (UDE), gefördert von der Deutschen Forschungsgemeinschaft. Sie wiesen nach, dass Kanten auf der Oberfläche die elektrische Leitfähigkeit beeinflussen, indem sie wie kleine Widerstände wirken – was aber gleichzeitig die Tür zu einem präzisen elektronischen Oberflächendesign öffnet. Ihre Erkenntnisse erschienen soeben in der Fachzeitschrift „Nature Communications“.

  • Novel Insulators with Conducting Edges

    Schematic of a higher-order topological insulator in the shape of a nanowire, with conducting channels on its edges. UZH

    Physicists at UZH are researching a new class of materials: Higher-order topological insulators. The edges of these crystalline solids conduct electric current without dissipation, while the rest of the crystal remains insulating. This could be useful for applications in semiconductor technology and for building quantum computers.

  • Novel Topological Insulator

    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)

    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.

  • Topological Quantum Chemistry

    Cover of the journal Nature from July 20, 2017. By courtesy of Nature / Illustration by JVG

    An international team of researchers has found a way to determine whether a crystal is a topological insulator — and to predict crystal structures and chemical compositions in which new ones can arise. The results, published July 20 in the journal Nature, show that topological insulators are much more common in nature than currently believed.

    Topological materials, which hold promise for a wide range of technological applications due to their exotic electronic properties, have attracted a great deal of theoretical and experimental interest over the past decade, culminating in the 2016 Nobel Prize in physics. The materials' electronic properties include the ability of current to flow without resistance and to respond in unconventional ways to electric and magnetic fields.

  • Understanding Insulators with Conducting Edges

    Artificial edge in an optical lattice (blue), filled with an ultracold quantum gas that consists of ‘spin-up’ particles (red) and ‘spin-down’ particles (green). Along the edge – and only there - 'spin-up' particles can only flow to the left, and ‘spin-down’ particles can only flow to the right. Credit: Bernhard Irsigler

    FRANKFURT. Insulators that are conducting at their edges hold promise for interesting technological applications. However, until now their characteristics have not been fully understood. Physicists at Goethe University have now modelled what are known as topological insulators with the help of ultracold quantum gases. In the current issue of Physical Review Letters, they demonstrate how the edge states could be experimentally detected.