Gold as an element is known and highly valued for more than 2500 years, and its popularity is based on its beautiful color and chemical inertness. It is well established that the golden color is, physically spoken, of relativistic origin. The surface of gold is unique, as it hosts states that have been understood as a prototype of surface states, named after William Shockley, Shockley surface states. However, until nowadays it was overseen that the gold surface states are very special, when relativity is taken into account.
These Shockley surface states can be reinterpreted as topologically derived surface states comparable with the robust surface state of a topological insulator, a recently discovered new quantum state. This new quantum state has caused a lot of excitement in the condensed matter community ranging from physics, materials science to chemistry.
However, no application of topological materials has been realized up to now. Gold and platinum, metals with the topological Shockley surface states, are used as standards in surface science and are also established materials for catalysis. Gold surfaces states are commonly employed to benchmark the capability of photoemission spectroscopy and scanning tunneling spectroscopy.
In a recent study on gold surface states, solid state chemistry research at the Max Planck Institute Chemical Physics of Solids in Dresden, with Binghai Yan co-affiliated at ShanghaiTech University, was combined with surface physics research of the University Kaiserslautern (department of Physics and State Research center OPTIMAS).
To prove a new theoretical prediction by Binghai Yan and the Dresden team, the Kaiserslautern team has used a unique photoemission technique, momentum-resolved two-photon photoemission, which allows us to measure the electronic structure in momentum space both below and above the Fermi energy. By combining an optical parametric oscillator laser system with a modern momentum microscope, it was feasible to map the dispersion of the surface states and to confirm experimentally their topological nature.
The discovery not only opens a pathway to new quantum materials, it will also initiate a discussion about the role of topological surfaces states in surface-related processes, such as adsorption and catalysis. Binghai Yan comments “I am fully convinced that the robust surface state in topological materials should positively influence catalysis. We will use this concept to search for new and sustainable materials than noble metals! ”
The work was published in Nature Communication online on Dec. 14th:
Topological States on the Gold Surface,
Binghai Yan, Benjamin Stadtmüller, Norman Haag, Sebastian Jakobs, Johannes Seidel, Dominik Jungkenn, Stefan Mathias, Mirko Cinchetti, Martin Aeschlimann and Claudia Felser, Nature Communication 6 (2015) 10167 | DOI: 10.1038/ncomms10167 and preprint arXiv:1504.01971
http://www.cpfs.mpg.de Prof. Dr. C. Felser, Dr. B. Yan
https://optimas.uni-kl.de Prof. Dr. M. Aeschlimann, Dr. I. Sattler
Ingrid Rothe | Max-Planck-Institut für Chemische Physik fester Stoffe
Strange but true: Turning a material upside down can sometimes make it softer
20.10.2017 | Universitat Autonoma de Barcelona
Metallic nanoparticles will help to determine the percentage of volatile compounds
20.10.2017 | Lomonosov Moscow State University
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
20.10.2017 | Information Technology
20.10.2017 | Materials Sciences
20.10.2017 | Interdisciplinary Research