Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Neutrons reveal unexpected magnetism in rare-earth alloy


A new study by a multi-institutional team, led by researchers from Brookhaven National Laboratory and Stony Brook University, has revealed exotic magnetic properties in a rare-earth based intermetallic compound. Similar studies suggest a better understanding of those types of behaviors could lead to applications in quantum computing and improved storage device technologies.

Researchers at the Department of Energy's Oak Ridge National Laboratory and their collaborators used neutron scattering to uncover magnetic excitations in the metallic compound ytterbium-platinum-lead (Yb2Pt2Pb). Surprisingly, this three-dimensional material exhibits magnetic properties that one would conventionally expect if the connectivity between magnetic ions was only one-dimensional. Their research is discussed in a paper published in the journal Science.

This illustration shows the one-dimensional Yb ion chain in the quantum magnet Yb2Pt2Pb. The Yb orbitals are depicted as the iso-surfaces, and the green arrows indicate the antiferromagnetically aligned Yb magnetic moments. The particular overlap of the orbitals allows the Yb moments to hop between the nearest and next nearest neighbors along the chain direction, resulting in the two and four spinon excitations.

Credit: ORNL/Genevieve Martin

An electron can theoretically be understood as a bound state of three quasiparticles, which collectively carry its identity: spin, charge and orbit. It has been known that the spinon, the entity that carries information about electron spin, can "separate" itself from the others under certain conditions in one-dimensional chains of magnetic ions such as copper (Cu2+) in an insulating host. Now, the new study reveals that spinons are also present in metallic Yb2Pt2Pb.

The experimental team included ORNL postdoctoral researcher and lead author Liusuo Wu, Georg Ehlers, and Andrey Podlesnyak, instrument scientists at ORNL's Spallation Neutron Source (SNS), a DOE Office of Science User Facility. The team made use of the neutrons' sensitivity to magnetic fluctuations at the atomic scale and the world-leading capabilities of the SNS Cold Neutron Chopper Spectrometer (CNCS) instrument.

Placing a sample of Yb2Pt2Pb in the neutron beam and carefully mapping the dependence of the scattering intensity on angle and time-of-flight revealed characteristic signatures of the magnetic collective excitations in the material.

"An electron's ability to exhibit quantum magnetic behavior like this depends on how many pairings it can make with its nearest neighbors," Wu said. "In a one-dimensional chain, each has only two neighbors, making quantum fluctuations much more dramatic."

With contributions from collaborators at Brookhaven, Stony Brook University, and the University of Amsterdam, the research team developed a picture of spinons propagating in a particular direction, and how a magnetic excitation spectrum was calculated, based on that model, and compared it to the experimental data.

"The element ytterbium, found in the 4f group of the periodic table, often makes an interesting ingredient in a material. Here, the leading magnetic interactions conspire with the crystal structure and the local anisotropy to create an effect we call geometric frustration," Ehlers said. "In materials research, this gives us a handle on the properties of a particular system and allows one, ultimately, to design materials with specific desirable properties."

As in electrons, the magnetic moments in neutrons originate from their spin-1/2, the smallest possible magnetic moment in an ion or electron shell. Combined with their high penetrating power--due to the fact they carry no charge--neutrons are an ideal probe to explore magnetism in atomic systems. Here, the interesting phenomena occur at low energies and low temperatures, which is why the cold neutrons at CNCS are well suited to study them.

"At higher temperatures, the thermal effects will blur what we're able to see, because the ions start moving about more if the material is warmer, hindering our ability to see the excitations clearly," Ehlers said.

Another advantage to the CNCS instrument is that it can detect neutron scattering patterns in all three spatial dimensions simultaneously, which, according to Ehlers, proved to be crucial in the team's investigation.

"At first we were really puzzled by our results," Wu said. "But once we started to understand and look at it from the right perspective, we could see how the electrons hop between overlapping orbitals on nearest Yb neighbors.

"Now that we have a better understanding of how this happens, we can search for other materials that demonstrate similar properties, which will hopefully lead to even bigger discoveries and better technologies."


Co-authors of the paper, titled "Orbital-Exchange and Fractional Quantum Number Excitations in an f-electron Metal, Yb2Pt2Pb" include lead author Liusuo Wu, William Gannon, Michael Brockmann, Jean-Sebastien Caux, Moosung Kim, Yiming Qiu, John R. Copley, Georg Ehlers, Andrey Podlesnyak, Alexei Tsvelik, Igor Zaliznyak, and Meigan Aronson.

Additional contributions and complementary measurements were obtained from DOE's Brookhaven National Laboratory, the National Institute of Standards and Technology, Stony Brook University, and the University of Amsterdam.

The research conducted at ORNL's Spallation Neutron Source was supported by DOE's Office of Science. The paper is available at

UT-Battelle manages ORNL for the DOE's Office of Science. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit

Media Contact

Jeremy Rumsey


Jeremy Rumsey | EurekAlert!

More articles from Materials Sciences:

nachricht Multitasking monolayers
25.07.2017 | Vanderbilt University

nachricht Flexible proximity sensor creates smart surfaces
25.07.2017 | Fraunhofer-Institut für Produktionstechnik und Automatisierung IPA

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

All Focus news of the innovation-report >>>



Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

Latest News

NASA mission surfs through waves in space to understand space weather

25.07.2017 | Physics and Astronomy

Strength of tectonic plates may explain shape of the Tibetan Plateau, study finds

25.07.2017 | Earth Sciences

The dense vessel network regulates formation of thrombocytes in the bone marrow

25.07.2017 | Life Sciences

More VideoLinks >>>