Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Large-scale cousin of elusive 'magnetic monopoles' found at NIST

08.10.2009
Any child can tell you that a magnet has a "north" and a "south" pole, and that if you break it into two pieces, you invariably get two smaller magnets with two poles of their own. But scientists have spent the better part of the last eight decades trying to find, in essence, a magnet with only one pole. A team working at the National Institute of Standards and Technology (NIST) has found one.*

In 1931, Paul Dirac, one of the rock stars of the physics world, made the somewhat startling prediction that "magnetic monopoles," or particles possessing only a single pole—either north or south—should exist.

His conclusion stemmed from examining a famous set of equations that explains the relationship between electricity and magnetism. Maxwell's equations apply to long-known electric monopole particles, such as negatively charged electrons and positively charged protons; but despite Dirac's prediction, no one has found magnetic monopole particles.

Now, a research team working at NIST's Center for Neutron Research (NCNR), led by Hiroaki Kadowaki of Tokyo Metropolitan University, has found the next best thing. By creating a compound that under certain conditions forms large, molecule-sized monopoles that behave exactly as the predicted particles should, the team has found a way to explore magnetic monopoles in the laboratory, not just on the chalkboard. (Another research team, working simultaneously, published similar findings in Science last month.**)

"These are not the monopole particles Dirac predicted—ours are huge in comparison—but they behave like them in every way," says Jeff Lynn, a NIST physicist. "Their properties will allow us to test how theoretical monopole particles should behave and interact."

The team created their monopoles in a compound made of oxygen, titanium and dysprosium that, when cooled to nearly absolute zero, forms what scientists call "spin ice." The material freezes into four-sided crystals (a pyramid with a triangular base) and the magnetic orientation, or "spin," of the ions at each of the four tips align so that their spins are balanced—two spins point inward and two outward. But using neutron beams at the NCNR, the team found they could knock one of the spins askew so that instead three point in, one out … "creating a monopole, or at least its mathematical equivalent," Lynn said.

Because every crystal pyramid shares its four tips with adjacent pyramids, flipping the spin of one tip creates an "anti-monopole" in the next pyramid over. The team has created monopole-antimonopole pairs repeatedly in a relatively large chunk of the spin ice, allowing them to confirm the monopoles' existence through advanced imaging techniques such as neutron scattering.

While the findings will not tell the team where in the universe to search for Dirac's still-elusive magnetic monopole particles, Lynn says that examining the spin ice will permit scientists to test certain predictions about monopoles. "Maxwell's equations indicate that monopoles should obey Coulomb's Law, which indicates their interaction should weaken as distance between them increases," he says. "Using the spin ice crystals, we can test ideas like this."

* H. Kadowaki, N. Doi, Y. Aoki, Y. Tabata, T.J. Sato, J.W. Lynn, K. Matsuhira and Z. Hiroi. Observation of magnetic monopoles in spin ice. Journal of the Physical Society of Japan,78, No. 10, Oct. 13, 2009. (The team first presented their findings in an invited talk at the International Conference on Neutron Scattering in May 2009.)

** D. J. P. Morris, et al. Dirac strings and magnetic monopoles in spin ice Dy2Ti2O7. Science, online publication Sept. 3, 2009.

Chad Boutin | EurekAlert!
Further information:
http://www.nist.gov

More articles from Physics and Astronomy:

nachricht Unconventional superconductor may be used to create quantum computers of the future
19.02.2018 | Chalmers University of Technology

nachricht Hubble sees Neptune's mysterious shrinking storm
16.02.2018 | NASA/Goddard Space Flight Center

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: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Japanese researchers develop ultrathin, highly elastic skin display

19.02.2018 | Information Technology

Dispersal of Fish Eggs by Water Birds – Just a Myth?

19.02.2018 | Ecology, The Environment and Conservation

Studying mitosis' structure to understand the inside of cancer cells

19.02.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>