Andrew Pell
Andrew Pell, Assistant Professor at the Department of Materials and Environmental Chemistry. Photo: Judith Schlagnitweit

The 2016 Nobel Prize for Physics was awarded for the use of advanced mathematical methods to explain exotic quantum phenomena in unusual phases of matter, such as superconductors, superfluids or thin magnetic films.

“Such phenomena have potential technological and sustainability applications in quantum computing, light sources and sensing, and for electric cars. In practice, these effects occur on and near the surfaces of materials called topological insulators”, say Andrew Pell, Assistant Professor at the Department of Materials and Environmental Chemistry, and together with Wassilios Papawassiliou, author of a new study on these materials.

“Tailoring of the surfaces via doping, varying the layer thickness or morphological changes of this class of materials directly affects their efficiency in a range of applications such as thermoelectric materials in cooling systems,  high-capacity battery materials, next generation photovoltaics and noble metal free heterogeneous nanocatalysts. Moreover the potential realization of Majorana Fermions, with dual particle-antiparticle nature, may enable fault-tolerant quantum computing by acting as a qubit, which in contrast to its classical counterpart, the bit, can occupy many states at once.”

In the article “Resolving Dirac electrons with broadband high-resolution NMR” published in the scientific journal Nature Communications, a team of scientists provides a new method, based on solid-state nuclear magnetic resonance, for observing so-called Dirac electrons, which are the electrons that sit on the surface of the materials, and showing how they interact with the material interior. The researchers are from Stockholm University, the National Center of Scientific Research Demokritos in Greece, the Korea Basic Science Institute in South Korea, the Josef Stefan Institute in Slovenia, and the Khalifa University of Science and Technology in the United Arab Emirates.

“This study reveals the presence of the structure of the Dirac electrons in much more detail than was possible previously using methods such as angle-resolved photoemission spectroscopy, particularly with regard to how far the Dirac electrons penetrate below the surface into the interior. This is crucial for fully understanding the topological properties of these materials.”

“The method can potentially be used to understand why certain topological materials are more effective than others, and how to improve them by fine tuning the surface structure. This will have many fields of application for quantum computing, light sources and sensing, and for developing electric cars”, says Andrew Pell.
 
The article “Resolving Dirac electrons with broadband high-resolution NMR” is published in the scientific journal Nature Communications.