Servicenavigation

Project Details

Back

Projekt Print View

SPP 1666:  Topological Insulators: Materials - Fundamental Properties - Devices

Subject Area Physics
Term from 2013 to 2023
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 220179758
 
Final Report Year 2024

Final Report Abstract

Topological insulators are materials that are electrically insulating in the bulk but can conduct electricity due to topologically protected electronic edge or surface states. These materials are important for a future type of electronics with significantly reduced energy consumption, among other reasons because the current is lossless. The topological states at the same time lead to quantum effects which can be exploited in metrology, where they can be used as for a new standard for electrical resistance. At present these standards require equipment to produce high magnetic fields, whereas the topological materials can use their built-in magnetic field. And the third major prospective application area is a topological form of quantum computing. Quantum computing can solve problems too difficult for conventional computers, for example in chemistry and pharmacology. There are many different approaches to quantum computers, however, at present one needs for all of them 100 to 1000 times more processing units than with topological quantum computing due to its principle stability against noise. Within the SPP1666 a new class of topological matter has been produced for the first time, the so-called topological Weyl semimetals, one example is niobium phosphide. These materials have special properties, for example there electrical conduction reacts very strongly to magnetic fields. Fundamentally new effects have been predicted, the observation of which has come closer in SPP1666. Another class of topological insulators discovered and classified for the first time in SPP 1666 are higher-order topological insulators. Here, novel topological states have been predicted. This enlarges the range of possible materials with topological effects enormously. One of the two main topological quantum effects, the quantum spin Hall effect could be improved with a new material synthesized for the first time in the SPP1666. The operating temperature could be increased from lowest temperatures almost a hundredfold and in principle reaches room temperature, judging by the spectroscopic data. The material is "bismuthene" with the honeycomb structure of graphite or graphene, but with an atomic layer of bismuth instead of carbon atoms. The other important topological quantum effect is called anomalous quantum Hall effect. It is the most promising candidate to replace the present quantum Hall effect standard for resistance. Here it is necessary to produce a magnetic topological material. This had so far only been possible by introducing magnetic impurities. In the SPP1666, stoichiometric magnetic topological insulators haven been discovered with a high concentration of the magnetic material instead of dilute impurities. Accordingly, the desired effects are significantly more pronounced and the application with a product has become more likely. This may lead to a new resistance normal but eventually could also be used for topological quantum computing. A topological quantum computer requires first of all to combine different properties such as superconductivity and magnetism with topological material. In the SPP1666 important observations have been made for various platforms which allow to distinguish the desired effects from other similarly looking effects.

Publications

 
 

Additional Information

© 2025 DFG Disclaimer / Copyright / Privacy Policy

Textvergrößerung und Kontrastanpassung