Triangular honeycombs: Physicists design novel quantum materials


Sep 14, 2021

(Nanowerk News) Researchers from the Würzburg-Dresden Cluster of Excellence ct.qmat–Complexity and Topology in Quantum Matter – have conceived and realized a brand new quantum materials: “Indenene”. Consisting of a single layer of the chemical aspect Indium, indenene enriches the household of the so-called topological insulators. The triangular lattice behind its tailored materials-design idea isn’t solely novel within the context of topological quantum supplies nevertheless it additionally provides vital benefits for future purposes. Ever because the discovery of the primary topological insulator this class of supplies has been attributed huge potential for the event of future electronics going past state-of-the-art expertise. and probably even for the belief of quantum computer systems. The research reporting the design and characterization of Indenene seems within the journal Nature Communications (“Design and realization of topological Dirac fermions on a triangular lattice”). The measured digital density (left) on the triangular indium lattice (proper). The determine highlights how electrons (in yellow) don’t sit on the atomic place however they quite occupy the voids in between (crimson and blue). As a consequence, an emergent honeycomb connectivity arises formally equal to the well-known graphene. At the identical time, this “hidden” honeycomb motif equips indenene with a a lot bigger bandgap, upgrading it to a superior quantum spin Hall system. (Image: ct.qmat)

Topological insulators–semiconductor expertise of the long run

Smartphones, notebooks and different digital units of our on a regular basis life strongly profit from the ever-increasing miniaturization of semiconductor units. This growth comes nonetheless at a worth: confining electrons enhances their scattering– cell telephones warmth up. Topological insulators maintain guarantees for a extra environment friendly and sustainable expertise. At odds with typical semiconductors, the present flows on their boundaries, with scattering turning into prohibited because of symmetry causes. In different phrases, issues keep cool! In 2007 Laurens Molenkamp, physicist on the University of Würzburg and member of the Cluster of Excellence, found the primary topological quantum materials, producing a worldwide resonance within the scientific group.

Indenene–a hidden honeycomb

In the seek for new topological supplies, a lot of the principle efforts hitherto have been specializing in two-dimensional atom layers in a honeycomb association. The motivation comes from graphene, the “Drosophila” of the quantum spin Hall programs, or extra merely, a single layer of the well-known graphite inside our old-style classical pencils. The analysis workforce in Würzburg pursued as a substitute another route: the theoretical physicists round Giorgio Sangiovanni have proposed to make use of a less complicated triangular atomic lattice. This thought has been put into follow by the experimental workforce of Ralph Claessen, spokesperson of ct.qmat’s Würzburg department. Using state-of-the-art molecular beam strategies, the researchers succeeded in depositing a single layer of indium atoms as triangular lattice on a silicon carbide crystal as assist – leading to indenene. Thanks to this new mixtures of constructing blocks and chemical parts, the related electrons don’t localize immediately on the indium positions however want to occupy thefree space in between them. From the angle of the electrons their cost fills the “negative” of the triangular indium lattice which is definitely a honeycomb lattice – hidden within the voids of the atomic construction. Project head Giorgio Sangiovanni explains this by way of the quantum mechanical nature of particles: “One can describe the indium electrons as waves that pile up in the voids of the triangular lattice where at first sight you would not expect them to be. Interestingly, the resulting ‘hidden’ honeycomb connectivity leads to a particularly robust topological insulator, more than graphene.”

Topological quantum supplies with distinctive benefits

The distinctive supplies design that has led to the synthesis of indenene can enhance the present technological standing within the discipline of topological electronics: In distinction to graphene, indenene wants to not be cooled all the way down to ultra-low temperatures to manifest its properties as a topological insulator. This is a consequence of the significantly easy triangular lattice which permits for big structural domains, usually a extreme bottleneck within the synthesis of different topological supplies. “We were indeed surprised, that such a simple atomic structure can display topological properties. This is an essential asset for the successful growth of perfect indenene films that can meet the demanding standards required for device nanofabrication. Furthermore, the use of silicon carbide as supporting substrate allows us to connect to established semiconductor technology,” says Ralph Claessen, commenting the scientific consequence.


The easy construction of indenene represents on the identical time a problem: as quickly as the only layer of indium atoms is available in contact with air, the fabric loses its particular properties. For this motive the researchers are at present creating an atomic capping layer that may defend indenene from undesirable contamination throughout its synthesis. An answer to those points will pave the best way in direction of a large-scale use of those topological quantum supplies.

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