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 Immortal quantum particles: the cycle of decay and rebirth
14.06.2019 | Technische Universität München

nachricht Small currents for big gains in spintronics
13.06.2019 | University of Tokyo

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: MPSD team discovers light-induced ferroelectricity in strontium titanate

Light can be used not only to measure materials’ properties, but also to change them. Especially interesting are those cases in which the function of a material can be modified, such as its ability to conduct electricity or to store information in its magnetic state. A team led by Andrea Cavalleri from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg used terahertz frequency light pulses to transform a non-ferroelectric material into a ferroelectric one.

Ferroelectricity is a state in which the constituent lattice “looks” in one specific direction, forming a macroscopic electrical polarisation. The ability to...

Im Focus: Determining the Earth’s gravity field more accurately than ever before

Researchers at TU Graz calculate the most accurate gravity field determination of the Earth using 1.16 billion satellite measurements. This yields valuable knowledge for climate research.

The Earth’s gravity fluctuates from place to place. Geodesists use this phenomenon to observe geodynamic and climatological processes. Using...

Im Focus: Tube anemone has the largest animal mitochondrial genome ever sequenced

Discovery by Brazilian and US researchers could change the classification of two species, which appear more akin to jellyfish than was thought.

The tube anemone Isarachnanthus nocturnus is only 15 cm long but has the largest mitochondrial genome of any animal sequenced to date, with 80,923 base pairs....

Im Focus: Tiny light box opens new doors into the nanoworld

Researchers at Chalmers University of Technology, Sweden, have discovered a completely new way of capturing, amplifying and linking light to matter at the nanolevel. Using a tiny box, built from stacked atomically thin material, they have succeeded in creating a type of feedback loop in which light and matter become one. The discovery, which was recently published in Nature Nanotechnology, opens up new possibilities in the world of nanophotonics.

Photonics is concerned with various means of using light. Fibre-optic communication is an example of photonics, as is the technology behind photodetectors and...

Im Focus: Cost-effective and individualized advanced electronic packaging in small batches now available

Fraunhofer IZM is joining the EUROPRACTICE IC Service platform. Together, the partners are making fan-out wafer level packaging (FOWLP) for electronic devices available and affordable even in small batches – and thus of interest to research institutes, universities, and SMEs. Costs can be significantly reduced by up to ten customers implementing individual fan-out wafer level packaging for their ICs or other components on a multi-project wafer. The target group includes any organization that does not produce in large quantities, but requires prototypes.

Research always means trying things out and daring to do new things. Research institutes, universities, and SMEs do not produce in large batches, but rather...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

 
Latest News

Concert of magnetic moments

14.06.2019 | Information Technology

Materials informatics reveals new class of super-hard alloys

14.06.2019 | Materials Sciences

New imaging modality targets cholesterol in arterial plaque

14.06.2019 | Medical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>