Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Neutrons zero in on the elusive magnetic Majorana fermion

09.06.2017

Neutron scattering has revealed in unprecedented detail new insights into the exotic magnetic behavior of a material that, with a fuller understanding, could pave the way for quantum calculations far beyond the limits of the ones and zeros of a computer's binary code.

A research team led by the Department of Energy's Oak Ridge National Laboratory has confirmed magnetic signatures likely related to Majorana fermions--elusive particles that could be the basis for a quantum bit, or qubit, in a two-dimensional graphene-like material, alpha-ruthenium trichloride.


As neutrons (blue line) scatter off the graphene-like honeycomb material, they produce a magnetic Majorana fermion (green wave) that moves through the material disrupting or breaking apart magnetic interactions between 'spinning' electrons.

Credit: ORNL/Jill Hemman

The results, published in the journal Science, verify and extend a 2016 Nature Materials study in which the team of researchers from ORNL, University of Tennessee, Max Planck Institute and Cambridge University first proposed this unusual behavior in the material.

"This research is a promise delivered," said lead author Arnab Banerjee, a postdoctoral researcher at ORNL. "Before, we suggested that this compound, alpha-ruthenium trichloride, showed the physics of Majorana fermions, but the material we used was a powder and obscured many important details. Now, we're looking at a large single crystal that confirms that the unusual magnetic spectrum is consistent with the idea of magnetic Majorana fermions."

Majorana fermions were theorized in 1937 by physicist Ettore Majorana. They are unique in that, unlike electrons and protons whose antiparticle counterparts are the positron and the antiproton, particles with equal but opposite charges, Majorana fermions are their own antiparticle and have no charge.

In 2006, physicist Alexei Kitaev developed a solvable theoretical model describing how topologically protected quantum computations could be achieved in a material using quantum spin liquids, or QSLs. QSLs are strange states achieved in solid materials where the magnetic moments, or "spins," associated with electrons exhibit a fluidlike behavior.

"Our neutron scattering measurements are showing us clear signatures of magnetic excitations that closely resemble the model of the Kitaev QSL," said corresponding author Steve Nagler, director of the Quantum Condensed Matter Division at ORNL. "The improvements in the new measurements are like looking at Saturn through a telescope and discovering the rings for the first time."

Because neutrons are microscopic magnets that carry no charge, they can be used to interact with and excite other magnetic particles in the system without compromising the integrity of the material's atomic structure. Neutrons can measure the magnetic spectrum of excitations, revealing how particles behave. The team cooled the material to temperatures near absolute zero (about minus 450 degrees Fahrenheit) to allow a direct observation of purely quantum motions.

Using the SEQUOIA instrument at ORNL's Spallation Neutron Source allowed the investigators to map out an image of the crystal's magnetic motions in both space and time.

"We can see the magnetic spectrum manifesting itself in the shape of a six-pointed star and how it reflects the underlying honeycomb lattice of the material," said Banerjee. "If we can understand these magnetic excitations in detail then we will be one step closer to finding a material that would enable us to pursue the ultimate dream of quantum computations."

Banerjee and his colleagues are pursuing additional experiments with applied magnetic fields and varying pressures.

"We've applied a very powerful measurement technique to get these exquisite visualizations that are allowing us to directly see the quantum nature of the material," said coauthor Alan Tennant, chief scientist for ORNL's Neutron Sciences Directorate. "Part of the excitement of the experiments is that they're leading the theory. We're seeing these things, and we know they're real."

###

The paper's authors also include ORNL's Jiaqiang Yan, Craig A. Bridges, Matthew B. Stone, and Mark D. Lumsden; Cambridge University's Johannes Knolle; the University of Tennessee's David G. Mandrus; and Roderich Moessner from the Max Planck Institute for the Physics of Complex Systems in Dresden.

The study was supported by DOE's Office of Science. The Spallation Neutron Source is a DOE Office of Science User Facility. UT-Battelle manages ORNL for the DOE 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 http://science.energy.gov/.

Media Contact

Jeremy Rumsey
rumseyjp@ornl.gov
865-576-2038

 @ORNL

http://www.ornl.gov 

Jeremy Rumsey | EurekAlert!

Further reports about: Max Planck Institute Neutron Spallation Neutron Source fermions

More articles from Physics and Astronomy:

nachricht Newfound Martian aurora actually the most common; sheds light on Mars' changing climate
13.12.2019 | NASA/Goddard Space Flight Center

nachricht Hubble watches interstellar comet Borisov speed past the sun
13.12.2019 | ESA/Hubble Information Centre

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

Im Focus: Virus multiplication in 3D

Vaccinia viruses serve as a vaccine against human smallpox and as the basis of new cancer therapies. Two studies now provide fascinating insights into their unusual propagation strategy at the atomic level.

For viruses to multiply, they usually need the support of the cells they infect. In many cases, only in their host’s nucleus can they find the machines,...

Im Focus: Cheers! Maxwell's electromagnetism extended to smaller scales

More than one hundred and fifty years have passed since the publication of James Clerk Maxwell's "A Dynamical Theory of the Electromagnetic Field" (1865). What would our lives be without this publication?

It is difficult to imagine, as this treatise revolutionized our fundamental understanding of electric fields, magnetic fields, and light. The twenty original...

Im Focus: Highly charged ion paves the way towards new physics

In a joint experimental and theoretical work performed at the Heidelberg Max Planck Institute for Nuclear Physics, an international team of physicists detected for the first time an orbital crossing in the highly charged ion Pr⁹⁺. Optical spectra were recorded employing an electron beam ion trap and analysed with the aid of atomic structure calculations. A proposed nHz-wide transition has been identified and its energy was determined with high precision. Theory predicts a very high sensitivity to new physics and extremely low susceptibility to external perturbations for this “clock line” making it a unique candidate for proposed precision studies.

Laser spectroscopy of neutral atoms and singly charged ions has reached astonishing precision by merit of a chain of technological advances during the past...

Im Focus: Ultrafast stimulated emission microscopy of single nanocrystals in Science

The ability to investigate the dynamics of single particle at the nano-scale and femtosecond level remained an unfathomed dream for years. It was not until the dawn of the 21st century that nanotechnology and femtoscience gradually merged together and the first ultrafast microscopy of individual quantum dots (QDs) and molecules was accomplished.

Ultrafast microscopy studies entirely rely on detecting nanoparticles or single molecules with luminescence techniques, which require efficient emitters to...

Im Focus: How to induce magnetism in graphene

Graphene, a two-dimensional structure made of carbon, is a material with excellent mechanical, electronic and optical properties. However, it did not seem suitable for magnetic applications. Together with international partners, Empa researchers have now succeeded in synthesizing a unique nanographene predicted in the 1970s, which conclusively demonstrates that carbon in very specific forms has magnetic properties that could permit future spintronic applications. The results have just been published in the renowned journal Nature Nanotechnology.

Depending on the shape and orientation of their edges, graphene nanostructures (also known as nanographenes) can have very different properties – for example,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

The Future of Work

03.12.2019 | Event News

First International Conference on Agrophotovoltaics in August 2020

15.11.2019 | Event News

Laser Symposium on Electromobility in Aachen: trends for the mobility revolution

15.11.2019 | Event News

 
Latest News

New yeast species discovered in Braunschweig, Germany

13.12.2019 | Life Sciences

Hubble watches interstellar comet Borisov speed past the sun

13.12.2019 | Physics and Astronomy

Saliva test shows promise for earlier and easier detection of mouth and throat cancer

13.12.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>