Researchers at the Goethe University in Frankfurt have discovered an important mechanism for superconductivity in a metallic compound containing ytterbium, rhodium and silicon.
Researchers at the Goethe University have discovered an important mechanism for superconductivity in a metallic compound containing ytterbium, rhodium and silicon. As reported by Cornelius Krellner and his colleagues in the current edition of the "Science" journal, the underlying concept of the quantum-critical point has long been discussed as a possible mechanism for high-temperature superconductivity.
Confirming this in YbRh2Si2 after 10 years of extensive research is thus a milestone in basic research. Due to its extremely low transition temperature of two-thousandths of a degree above absolute zero, the material will have no practical relevance.
"The ytterbium atoms are essential to the material properties because they are magnetic – and for a particularly fascinating reason", Prof. Krellner from the Institute for Physics at Goethe University explains. This is because the transition to the magnetized state (phase transition) takes place at such low temperatures that temperature-related movements of the tiny atomic magnets no longer play a role.
This is what distinguishes this phase transition from all other known transitions, such as the freezing of water into ice. Quantum fluctuations dominate at temperatures near absolute zero (minus 273 degrees). These are so strong that nature attempts to take on alternative ordered fundamental states.
Superconductivity is a potential collective state which can arise at a quantum-critical point. "After we discovered it in YbRh2Si2, we were able to show that unconventional superconductivity is a general mechanism at a quantum-critical point", Krellner explains. The elaborate low-temperature measurements were taken in collaboration with the Walther-Meißner Institute for Low Temperature Research in Garching.
Cornelius Krellner studied YbRh2Si2 10 years ago while working towards his doctorate at the Max-Planck Institute for Chemical Physics of Solids. At the time, he was growing single crystals of the compound. The quality and size of these was essential to measuring the material properties in the first place.
"We were all very enthusiastic when we saw the first indications of superconductivity, and I put all my efforts into growing even better and larger single crystals", remembers Krellner, who has headed the Crystal and Materials Laboratory at Goethe University since 2012.
That it took so long after that to produce the final proof of unconventional superconductivity was due to the fact that the measurements are extremely time-consuming. Furthermore, it was necessary to study the superconductivity with different techniques in order to show that it really was a case of unconventional superconductivity.
Krellner and his team use a special method to grow the crystals. It prevents ytterbium from vaporizing at the required high temperatures of 1500 degrees Celsius. "We are currently the only ones in Europe with the capability of producing single crystals of YbRh2Si2" Krellner is proud to tell us.
Over the next few years, he and his colleagues want to study the magnetic order above the superconducting range. Physicists will also study the superconductivity itself in greater detail over the next few years – a task which will be enabled by the pure and large single crystals from AG Krellner.
Pictures are available for downloading here: (We will insert a link)
Publication: E. Schuberth et al., Emergence of Heavy-Electron Superconductivity by the Ordering of Nuclear Spins. Science (2016).
Information: Prof. Dr. Cornelius Krellner, Institute of Physics, Phone.: (069) 798-47295, firstname.lastname@example.org.
Goethe University has a strong background in research and is based in the European financial center of Frankfurt. Founded in 1914 with purely private funds by liberally-oriented Frankfurt citizens, it is dedicated to research and education under the motto "Science for Society" and to this day continues to function as a "citizens’ university". Many of the early benefactors were Jewish. Over the past 100 years, Goethe University has done pioneering work in the social and sociological sciences, chemistry, quantum physics, brain research and labour law. It gained a unique level of autonomy on 1 January 2008 by returning to its historic roots as a "foundation university". Today, it is among the top ten in external funding and among the top three largest universities in Germany, with three clusters of excellence in medicine, life sciences and the humanities.
Publisher: The President of Goethe University, Editor: Dr. Anne Hardy, Contact for Science Communications, Marketing and Communications Department, Theodor-W.-Adorno-Platz 1, 60629 Frankfurt am Main, Phone: +49(0)69 798-12498, Fax: (069) 798-761 12531, email@example.com.
Dr. Anne Hardy | idw - Informationsdienst Wissenschaft
A tale of two pulsars' tails: Plumes offer geometry lessons to astronomers
18.01.2017 | Penn State
Studying fundamental particles in materials
17.01.2017 | Max-Planck-Institut für Struktur und Dynamik der Materie
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
18.01.2017 | Power and Electrical Engineering
18.01.2017 | Materials Sciences
18.01.2017 | Life Sciences