An experiment has confirmed that spinons, particle-like magnetic excitations, can be confined in a magnetic insulator similar to the way elementary quarks are confined within individual protons and neutrons. The finding, in a well-described magnetic system, may offer new ways to explore Quantum Chromodynamics, the theory that describes the fundamental interactions of quarks.
The observations of spinon confinement were made at the Science and Technology Facilities Councils Rutherford Appleton Laboratory in the United Kingdom by an international team of physicists. The team realized serendipitously that a theory developed 12 years earlier by theoretical physicist Alexei Tsevelik, now at the U.S. Department of Energy's Brookhaven National Laboratory, and collaborators accurately predicted the current findings. Together, the scientists describe the theory and their new observations in the November 29th issue of Nature Physics.
"The concept of confinement is one of the central ideas in modern physics, being at the core of the theory of nuclear forces," Tsvelik said. "In certain systems, when constituent particles are bound together by an interaction whose strength increases with increasing particle separation, individual particles cannot exist in a free state and therefore can be observed only indirectly."
The most famous example of confinement is of quarks which are held together in protons and neutrons, for example, by the strong force, a force that grows stronger with increasing distance.
"It has been interesting for us that a similar situation of confinement can be modeled in condensed matter systems," Tsvelik said. "Instead of quarks being confined in protons and neutrons, we have other quantum entities that act just like particles -- elementary excitations of magnetic systems called spinons."
In the case of the current experiment, the spinons exist on parallel chains of copper-oxide separated by inert calcium. Spinons on individual chains are not confined, but as soon as two chains are brought together to form ladder-like arrangements, the inter-ladder interactions confine the spinons.
"That is, the spinons can appear now only in pairs and cannot fly away from each other too far," Tsvelik said. "The result of this confinement is a particle we call a magnon. It is like two quarks pairing up to form a meson."
The original theory paper published by Tsvelik and collaborators 12 years ago described the magnetic excitation spectrum of such a system in detail. The team performing the experiments at Rutherford observed a signature that fit that description.
"Now that we have an example of confinement in a condensed matter system, our next step is to check further predictions of the theory to make sure there are no unpleasant surprises," Tsvelik said. The scientists will also measure the responses in other compounds to see if they observe similar effects.
Tsvelik's research is funded by the DOE Office of Science.
Upon publication, the paper can be downloaded at: http://dx.doi.org/10.1038/NPHYS1462
The Science and Technology Facilities Council ensures the UK retains its leading place on the world stage by delivering world-class science; accessing and hosting international facilities; developing innovative technologies; and increasing the socio-economic impact of its research through effective knowledge exchange partnerships. The Council has a broad science portfolio including Astronomy, Particle Physics, Particle Astrophysics, Nuclear Physics, Space Science, Synchrotron Radiation, Neutron Sources and High Power Lasers. In addition the Council manages and operates three internationally renowned laboratories: The Rutherford Appleton Laboratory, Oxfordshire; The Daresbury Laboratory, Cheshire; and The UK Astronomy Technology Centre, Edinburgh. For more information, visit: http://www.stfc.ac.uk.
One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry, and government researchers. Brookhaven is operated and managed for DOEs Office of Science by Brookhaven Science Associates, a limited-liability company founded by the Research Foundation of the State University of New York, for and on behalf of Stony Brook University, the largest academic user of Laboratory facilities; and Battelle Memorial Institute, a nonprofit, applied science and technology organization. Visit Brookhaven Lab's electronic newsroom for links, news archives, graphics, and more (http://www.bnl/gov/newsroom), or follow Brookhaven Lab on Twitter (http://twitter.com/BrookhavenLab).
* Additional news release on this research from Helmholtz-Zentrum Berlin: http://www.bnl.gov/bnlweb/pubaf/pr/docs/PR-HZB.pdf
A 100-year-old physics problem has been solved at EPFL
23.06.2017 | Ecole Polytechnique Fédérale de Lausanne
Quantum thermometer or optical refrigerator?
23.06.2017 | National Institute of Standards and Technology (NIST)
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
23.06.2017 | Physics and Astronomy
23.06.2017 | Physics and Astronomy
23.06.2017 | Information Technology