Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

When old is new again

04.10.2010
A fundamental effect associated with electrons also occurs in non-charged particles—a potential boon for spintronics

Just as electronics revolutionized computing and communications technology, spintronics is touted to follow suit. This relatively new field involves manipulating the flow of a magnetism-related property called ‘spin’.

In magnons, a spintronic counterpart of electrons, Naoto Nagaosa from the RIKEN Advanced Science Institute (ASI) in Wako and his colleagues have observed an effect first seen with electrons over 130 years ago: the Hall effect1. The Hall effect is used in sensitive detectors, so the researchers believe their finding could lead to new applications for magnetic insulators.

The Hall effect arises because a charge-carrying particle such as an electron experiences a force perpendicular to its direction of motion as it moves through a magnetic field of a conducting material. The result is a build-up of charges of opposite signs on either side of the material, which creates a measureable electric field. Magnons, however, have no charge, so an analogous effect had never been observed previously.

“The Hall effect is one of the most fundamental phenomena in condensed matter physics,” explains Nagaosa. “It is important to study to what extent we can apply ideas from conventional electronics to spintronics.” Nagaosa, along with Yoshinori Tokura also from ASI, Yoshinori Onose and co-workers from The University of Tokyo, and Hosho Katsura from the University of California, Santa Barbara, USA, studied the magnetic and thermal properties of the insulating ferromagnet Lu2V2O7 at low temperatures. Rather than the electric field associated with the conventional effect, the Hall effect manifested in this material as a thermal conductivity gradient across the sample. This difference occurs because the magnons carry heat, rather than charge.

The researchers showed that the size of the effect is not proportional to the applied magnetic field, but has a maximum at relatively low fields. This supports the hypothesis that magnons, influenced by the relativistic interaction, are responsible because the number of magnons is known to be reduced at these low-level magnetic fields. They also observed that the conductivity gradient started to decrease at higher fields. This observation allowed Nagaosa and colleagues to rule out lattice vibrations, or phonons, as another possible underlying cause of the experimental results: a phonon-induced thermal conductivity gradient would be expected to continue to increase with magnetic field.

“According to our theoretical prediction, only certain types of the crystal structure show this magnon Hall effect,” says Nagaosa. “To confirm this theory, we next aim to check that the phenomenon is absent in more conventional structures such as a cubic lattice.”

The corresponding author for this highlight is based at the Theoretical Design Team, RIKEN Advanced Science Institute

Journal information

1. Onose, Y., Ideue, T., Katsura, H., Shiomi, Y., Nagaosa, N. & Tokura, Y. Observation of the magnon Hall effect. Science 329, 297–299 (2010)

gro-pr | Research asia research news
Further information:
http://www.rikenresearch.riken.jp/eng/research/6400
http://www.researchsea.com

More articles from Physics and Astronomy:

nachricht Airborne thermometer to measure Arctic temperatures
11.01.2017 | Moscow Institute of Physics and Technology

nachricht Next-generation optics offer the widest real-time views of vast regions of the sun
11.01.2017 | New Jersey Institute of Technology

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: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

Im Focus: Bacterial Pac Man molecule snaps at sugar

Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.

The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...

Im Focus: Newly proposed reference datasets improve weather satellite data quality

UMD, NOAA collaboration demonstrates suitability of in-orbit datasets for weather satellite calibration

"Traffic and weather, together on the hour!" blasts your local radio station, while your smartphone knows the weather halfway across the world. A network of...

Im Focus: Repairing defects in fiber-reinforced plastics more efficiently

Fiber-reinforced plastics (FRP) are frequently used in the aeronautic and automobile industry. However, the repair of workpieces made of these composite materials is often less profitable than exchanging the part. In order to increase the lifetime of FRP parts and to make them more eco-efficient, the Laser Zentrum Hannover e.V. (LZH) and the Apodius GmbH want to combine a new measuring device for fiber layer orientation with an innovative laser-based repair process.

Defects in FRP pieces may be production or operation-related. Whether or not repair is cost-effective depends on the geometry of the defective area, the tools...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

Solar Collectors from Ultra-High Performance Concrete Combine Energy Efficiency and Aesthetics

16.01.2017 | Trade Fair News

3D scans for the automotive industry

16.01.2017 | Automotive Engineering

Nanoparticle Exposure Can Awaken Dormant Viruses in the Lungs

16.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>