Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Exotic material keeps frustrated electrons flipping

13.02.2008
RIKEN scientists have discovered a new state of matter with unusual magnetic properties—its constituent electrons are in a continuous state of flux, even at incredibly cold temperatures.

Magnetic, temperature and structural studies have yielded new insights on the material sodium iridium oxide

RIKEN scientists have discovered a new state of matter with unusual magnetic properties—its constituent electrons are in a continuous state of flux, even at incredibly cold temperatures.

As electrons spin, they generate a magnetic field which can point ‘up’ or ‘down’. Within solid materials, an electron will generally try to adopt the opposite spin orientation to its neighbor, just as two bar magnets will flip around so that north and south poles line up next to each other.

In more common lattice structures, where atoms stack up like oranges on a greengrocers stall, it’s easy for electrons to achieve this ordered arrangement. But in certain materials, the arrangement of atoms can make it impossible for the electrons to line up with all of their neighbors, and they are said to be ‘frustrated’.

One example of a frustrated material contains a network of atoms arranged into corner-sharing triangles. This is called a kagome structure after a type of Japanese basket that has the same pattern (Fig. 1).

The electrons’ response to this frustration is to constantly flip their magnetic fields to reduce the repulsion between them. In this ‘quantum spin-liquid state’, the quantum effect is expected to stop flipping electrons from freezing out into a static arrangement even at absolute zero (-273.15 ˚C—the coldest temperature possible). Several materials have been claimed to contain possible quantum spin-liquid states, but none have been confirmed.

Hidenori Takagi and Yoshihiko Okamoto of RIKEN’s Discovery Research Institute, Wako, and colleagues, have now found that sodium iridium oxide (Na4Ir3O8) exhibits quantum spin-liquid behavior, even when cooled to -271 ˚C. This was confirmed by magnetic, temperature and structural studies, involving both neutron and x-ray diffraction.

The material contains a network of iridium atoms that form a three-dimensional pattern of corner-shared triangles—dubbed a hyperkagome lattice (Fig. 2), which can be viewed as a slightly twisted—but different structure—to the kagome structure, explains Takagi. Theoretical calculations are consistent with this type of structure showing spin-liquid behavior.

“We believe it is the strongest candidate [for a quantum spin liquid],” says Takagi.

The scientists say that the material is “a fascinating playground for quantum magnetism”, and now hope to study the spin-liquid state further. This should to help build up a detailed description of the phenomenon using quantum theory, describing on a subatomic level exactly how the spinning electrons interact with each other.

1. Okamoto, Y., Nohara, M., Aruga-Katori, H. & Takagi, H. Spin-liquid state in the S = 1/2 hyperkagome antiferromagnet Na4Ir3O8. Physical Review Letters 99, 137207 (2007).

Saeko Okada | ResearchSEA
Further information:
http://www.riken.jp
http://www.researchsea.com

More articles from Materials Sciences:

nachricht High-tech sensing illuminates concrete stress testing
20.07.2017 | University of Leeds

nachricht Here's a tip: Indented cement shows unique properties
20.07.2017 | Rice University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

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...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

Im Focus: Laser-cooled ions contribute to better understanding of friction

Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision

Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

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

Leipzig HTP-Forum discusses "hydrothermal processes" as a key technology for a biobased economy

12.07.2017 | Event News

 
Latest News

Researchers create new technique for manipulating polarization of terahertz radiation

20.07.2017 | Information Technology

High-tech sensing illuminates concrete stress testing

20.07.2017 | Materials Sciences

First direct observation and measurement of ultra-fast moving vortices in superconductors

20.07.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>